Luna is the last surviving full-sized wooden ship-docking tug on the US Gulf and Atlantic coasts and was the world's first diesel-electric tugboat built for commercial service. These two distinctions have led to designation of Luna as a US National Historic Landmark. Today Luna is preserved in Boston Harbor, where her rehabilitation process has been underway since the tug was rescued from being broken up in 1995. Luna is the responsibility of the Luna Preservation Society[3] and its progress is recorded in their website. Due to her wartime service with a civilian crew, Luna is also a member of the Naval Historic Vessel Association.

Luna was designed by John G. Alden (1884–1962), one of America's greatest and most prolific yacht designers, but was heavily influenced by the preferences of the tug's owner, the Mystic Steamship Company, and its subsidiary Boston Tow Boat Company. As a result, Luna's aesthetics embody the classical sweeping profile of the American harbor tug, the tugboat also had a very innovative propulsion plant: two diesel engines, each turning a generator and exciter to create DC current, which was then shunted (via prototypical switchboards) to a single DC motor (weighing 20 tons) attached to a single propeller shaft. The project was a showpiece for Thomas Edison's General Electric Corporation, which seized the challenge to design, build and deliver the components, in conjunction with their control subcontractors. Six years after Luna's delivery, GE reported that there were 33 diesel-electric tugs in service, 21 of which were GE installations.

Luna's wooden hull and deckhouses were built by the M.M. Davis Shipbuilding Company in Solomons, Maryland, the empty hull was towed from the Chesapeake to East Boston for outfitting at the Bethlehem Steel Shipyard in East Boston.

Upon completion, Luna was delivered to the Mystic Steamship Company of Boston as the first diesel-powered tug in their fleet. All the other tugs in the Mystic Steamship fleet - commercially known as the Boston Towboat Company - were powered by coal and oil-fired boilers and steam engines, the Mystic Steamship Company could trace its roots to the Boston Towboat Company, which had been founded by Boston's maritime executives to assure salvage, icebreaking, and ship towing services in 1857. The Mystic Steamship Company operated coal-carrying colliers and coal barges to transport coal from railroad piers in New York Harbor, Philadelphia, Baltimore and Newport News, this coal was used as a fuel, and as the basis to make lamp gas from coal and coke. Later, Boston Towboat was operated by Eastern Enterprises, owners of Boston Gas and various maritime operations, which is active to this day as Eastern Enterprises.

Luna and her sister, Venus, were the most powerful, reliable, and efficient boats in the Boston Towboat fleet and therefore were the first boats to be assigned every day. The majority of the tug's work involved docking and undocking ships in every part of greater Boston Harbor, from Salem's coal-fired powerplants and industries in the north, to Plymouth harbor in the south. Most of the time, the tugs were busy pushing and towing tankers, freighters, refrigerated cargo ships, passenger liners, warships, and large barges within Boston Harbor including Chelsea Creek, the Mystic River, the Charles River and Fort Point Channel. They occasionally operated on assignments as far away as Maine and New York.

During World War II, Luna was mobilized for service with the US Navy and US Army. She was used as a civilian-crewed and privately owned and managed tugboat at shipyards, repair yards, terminals, piers and anchorages from Bath, Maine to the Cape Cod Canal. Luna handled the many ships launched at the yards, guided damaged ships into drydock, took over the towing of damaged ships in the harbor from seagoing rescue tugs, undocked warships, transports and troopships bound for war, towed barges laden with ammunition, stores and fuel. She greeted returning warships and troop ships at the end of the war. Luna was the flagship of the Boston Towboat fleet until the end of the war, when modern surplus war-built tugs were sold off by the government. General Electric was so proud of Luna that its marine advertisements featured Luna into the early 1950s, a period that spanned almost two decades, during the 1930s, post war 1940s and early 1950s, Luna assisted the USS Constitution with her annual turnaround.[4]

As more powerful diesel tugs and diesel-electric tugs were delivered to Boston Towboat, Luna was gradually relegated to back-up status and was retired in 1971, the tug was then used as an office and floating home, until it was acquired by a non-profit research institution in 1979. She was maintained on a shoestring budget by Captain Frances Rose Gage and many volunteers but sank twice in this period, the Luna Preservation Society took responsibility for her in 1995. Luna was declared a National Historic Landmark in 1989.[2][4] Since being rescued from a graving dock in East Boston in early 1995, Luna has been rehabilitated for her role in Boston Harbor as an operating Landmark and educational vessel.

In October, 2000 Luna was towed to Boothbay Harbor, Maine to begin a major overhaul of her hull structure and returned to Boston in May 2002; in October 2007, Luna began a major rehabilitation of all three decks (pilothouse roof, boat deck, and main deck) as well as deckhouse structure and coamings. This work was completed in May 2008 and was followed immediately by cleaning and coating of all original machinery and steel structure in her engine room. Plans are being developed for the installation of a small, modern diesel engine for "shadow" propulsion of the tug, permitting the original machinery to be restored to its original appearance, despite its corrosion damage suffered when the tug sank in fresh and salt water in the late 1980s and early 1990s.[needs update]

There are two Winton 6-cylinder, in-line diesel engines produce 380 hp (280 kW) each. At 300 rpm, they create the power that is converted into direct electric current. Two General Electric direct current generators, of 250 kilowatts each, are connected to the main engines and create the electricity that is delivered to the main propulsion motor. Aft of each generator is a General Electric exciters, directly connected to a diesel engine. Exciters induce a current in the rotating armature of the generators.

The engines are two-cycle and have fresh water cooling by a sea water heat exchanger. Salt water/fresh water condensers are installed port and starboard to cool the fresh water that is circulated through the diesel engines to cool the engine blocks, the fresh water loops are surrounded by circulating sea water.

One General Electric deadfront[clarification needed]switchboard controls the creation of electricity by the generators and the delivery of electricity to the motor which is a General Electric 600 hp (450 kW) DC electric motor with armatures. It is directly connected to the propeller shaft and turns the iron, four-bladed propeller, the motor is controlled directly from the steering stations.

Two compressors and four compressed air storage tanks are used to crank-start the diesel engines prior to the introduction of diesel fuel. Luna's horn is also air-powered. A set of batteries is installed to store emergency electric power for lighting and starting the compressors.

Luna is equipped with various pumps, including a fuel transfer pump, to shift fuel from one fuel tank to another and to a day tank, a bilge and salvage pump, to pump water from the tug and from barges and ships in case of an emergency, and a fire pump to deliver water to several hydrants for fire-fighting and deck washing. Galley water is delivered by hand pump.

There is also a steering engine which is an electro-hydraulic motor-driven winch that takes directions from the steering wheel and pulls a steering cable connected through pulleys to the tug's rudder from port to starboard.

Several different kinds of wood are used in the construction of the Luna. White Oak is a strong, dense wood used for outboard hull planking, pilothouse planking, keels and keelsons, hull structure and frames, and knees to connect right angles. Cypress is a highly rot-resistant wood used for main deckhouse planking, boat deck (also called the "Texas") and pilothouse decking, and bulwark planking (original). It is being replaced by cedar during restoration. Douglas Fir is a straight-grained and strong wood used for main deck planking, and fore and aft masts. Live Yellow Pine is rot-resistant and flexible; it is used for inboard hull "ceiling" planking, deck beams, deckhouse coamings, and deckhouse studs. Locust is a tough wood that expands. It is used for wooden treenails, also called trunnels, to fasten wooden planks to frames in drilled holes.[citation needed]

National Register of Historic Places
–
The National Register of Historic Places is the United States federal governments official list of districts, sites, buildings, structures, and objects deemed worthy of preservation. The passage of the National Historic Preservation Act in 1966 established the National Register, of the more than one million properties on the National Register,80,00

National Historic Landmark
–
A National Historic Landmark is a building, district, object, site, or structure that is officially recognized by the United States government for its outstanding historical significance. Of over 85,000 places listed on the countrys National Register of Historic Places, a National Historic Landmark District may include contributing properties that

Chelsea, Massachusetts
–
Chelsea is a city in Suffolk County, Massachusetts, United States, directly across the Mystic River from the city of Boston. As of 2013, Chelsea had an population of 36,828. It is also the second most densely populated city in Massachusetts behind Somerville, with a total area of just 2.5 square miles, Chelsea is the smallest city in Massachusetts

Geographic coordinate system
–
A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a

1.
Longitude lines are perpendicular and latitude lines are parallel to the equator.

Tugboat
–
A tug is a boat or ship that maneuvers vessels by pushing or towing them. Tugboats are powerful for their size and strongly built, and some are ocean-going, some tugboats serve as icebreakers or salvage boats. Early tugboats had steam engines, but today most have diesel engines, many tugboats have firefighting monitors, allowing them to assist in f

Boston
–
Boston is the capital and most populous city of the Commonwealth of Massachusetts in the United States. Boston is also the seat of Suffolk County, although the county government was disbanded on July 1,1999. The city proper covers 48 square miles with a population of 667,137 in 2015, making it the largest city in New England. Alternately, as a Comb

Thomas Edison
–
Thomas Alva Edison was an American inventor and businessman, who has been described as Americas greatest inventor. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and the long-lasting, practical electric light bulb. Edison was an inventor, holding 1,093 US patents in his

4.
Photograph of Edison with his phonograph (2nd model), taken in Mathew Brady 's Washington, DC studio in April 1878.

General Electric
–
General Electric, often abbreviated as GE, is an American multinational conglomerate corporation incorporated in New York and headquartered in Boston, Massachusetts. In 2011, GE ranked among the Fortune 500 as the 68th-largest firm in the U. S. by gross revenue, as of 2012, the company was listed the fourth-largest in the world among the Forbes Glo

Solomons, Maryland
–
Solomons, also known as Solomons Island, is an unincorporated community and census-designated place in Calvert County, Maryland, United States. The population was 2,368 at the 2010 census, up from 1,536 at the 2000 census, Solomons is a popular weekend destination spot in the Baltimore–Washington metropolitan area. Solomons is located at the tip of

1.
Sculpture On Watch, commemorating the World War II U.S. Naval Amphibious Training Base, 1942–1945, by Antonio Tobias Mendez

Salem, Massachusetts
–
Salem is a coastal city in Essex County, Massachusetts, in the United States, located on Massachusetts North Shore. It is a New England bedrock of history and is considered one of the most significant seaports in Puritan American history, the citys reported population was 41,340 at the 2010 census. Salem and Lawrence are the county seats of Essex C

4.
Title page of A Modest Enquiry Into the Nature of Witchcraft by John Hale (Boston, 1702)

Plymouth, Massachusetts
–
Plymouth /ˈplɪməθ/ is a town in Plymouth County, Massachusetts, United States. Plymouth holds a place of prominence in American history, folklore, and culture. Plymouth was the site of the founded in 1620 by the Pilgrims. Plymouth is where New England was first established and it is the oldest municipality in New England and one of the oldest in th

1.
Court Street, Plymouth Center, 2009

2.
Flag

3.
The First Thanksgiving, painted by Jean Leon Gerome Ferris (1863–1930). The First Thanksgiving took place in Plymouth in 1621.

4.
A Plymouth deed signed by Josiah Cotton as Register of Deeds, Courtesy of Shiwei Jiang

Chelsea Creek

1.
View across toward Chelsea from East Boston.

Mystic River
–
The Mystic River is a 7. 0-mile-long river in Massachusetts, in the United States. Its name derives from the Wampanoag word muhs-uhtuq, which translates to big river, in an Algonquian language, Missi-Tuk means a great river whose waters are driven by waves, alluding to the original tidal nature of the Mystic. It lies to the north of and flows paral

Charles River
–
The Charles River is an 80 mi long river in eastern Massachusetts. From its source in Hopkinton the river flows in a direction, traveling through 23 cities. Thirty-three lakes and ponds and 35 municipalities are entirely or partially part of the Charles River drainage basin, despite the rivers length and relatively large drainage area, its source i

Fort Point Channel
–
Fort Point Channel is a maritime channel separating South Boston from downtown Boston, Massachusetts, feeding into Boston Harbor. The south part of it has gradually filled in for use by the South Bay rail yard. At its south end, the channel once widened into South Bay, the Boston Tea Party occurred at its northern end. The channel is surrounded by

1.
Fort Point Channel, as seen from the south end looking north.

2.
Fort Point Channel

3.
Old Northern Avenue Bridge

4.
Fort Point as it relates to how Boston was filled in.

Maine
–
Maine is the northernmost state in the New England region of the northeastern United States. Maine is the 39th most extensive and the 41st most populous of the U. S. states and territories and it is bordered by New Hampshire to the west, the Atlantic Ocean to the east, and the Canadian provinces of New Brunswick and Quebec to the north. Maine is th

New York (state)
–
New York is a state in the northeastern United States, and is the 27th-most extensive, fourth-most populous, and seventh-most densely populated U. S. state. New York is bordered by New Jersey and Pennsylvania to the south and Connecticut, Massachusetts, and Vermont to the east. With an estimated population of 8.55 million in 2015, New York City is

World War II
–
World War II, also known as the Second World War, was a global war that lasted from 1939 to 1945, although related conflicts began earlier. It involved the vast majority of the worlds countries—including all of the great powers—eventually forming two opposing alliances, the Allies and the Axis. It was the most widespread war in history, and directl

US Navy
–
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U. S. Navy is the largest, most capable navy in the world, the U. S. Navy has the worlds largest aircraft carrier fleet, with ten in service, two in the reserve fleet, and three new carriers

US Army
–
The United States Army is the largest branch of the United States Armed Forces and performs land-based military operations. After the Revolutionary War, the Congress of the Confederation created the United States Army on 3 June 1784, the United States Army considers itself descended from the Continental Army, and dates its institutional inception f

Bath, Maine
–
Bath is a city in Sagadahoc County, Maine, in the United States. The population was 8,514 at the 2010 census, and 8,357 as of 2013 and it is the county seat of Sagadahoc County, Which includes one city and 10 towns. The city is popular with tourists, many drawn by its 19th-century architecture and it is home to the Bath Iron Works and Heritage Days

1.
Bath City Hall

2.
Seal

3.
Waterfront in 1907

4.
Front Street c. 1920

Cape Cod Canal
–
The Cape Cod Canal is an artificial waterway in the state of Massachusetts connecting Cape Cod Bay in the north to Buzzards Bay in the south. Part of the Atlantic Intracoastal Waterway, the approximately 7 mile long canal traverses the narrow neck of land joining Cape Cod to the states mainland. Most of its length follows tidal rivers widened to 48

USS Constitution
–
USS Constitution is a wooden-hulled, three-masted heavy frigate of the United States Navy, named by President George Washington after the Constitution of the United States of America. She is the worlds oldest commissioned naval vessel afloat, Constitution was launched in 1797, one of six original frigates authorized for construction by the Naval Ac

Boothbay Harbor, Maine
–
Boothbay Harbor is a town in the county of Lincoln, state of Maine, in the United States. The population was 2,165 at the 2010 census, during summer months, the entire Boothbay Harbor region is a popular yachting and tourist destination. The community is served by the 633 exchange in Area Code 207, the area was part of Cape Newagen, where the Engli

Winton Motor Carriage Company
–
The Winton Motor Carriage Company was a pioneer United States automobile manufacturer based in Cleveland, Ohio. Winton was one of the first American companies to sell a motor car, scottish immigrant Alexander Winton, owner of the Winton Bicycle Company, turned from bicycle production to an experimental single-cylinder automobile before starting his

Diesel engine
–
Diesel engines work by compressing only the air. This increases the air temperature inside the cylinder to such a degree that it ignites atomised diesel fuel that is injected into the combustion chamber. This contrasts with spark-ignition engines such as an engine or gas engine. In diesel engines, glow plugs may be used to aid starting in cold weat

4.
Diesel's original 1897 engine on display at the Deutsches Museum in Munich, Germany

Electric generator
–
In electricity generation, a generator is a device that converts mechanical energy to electrical energy for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines, the first electromagnetic generator, the Faraday disk, was built in 1831 by British scientist Michael

3.
The Faraday disk was the first electric generator. The horseshoe-shaped magnet (A) created a magnetic field through the disk (D). When the disk was turned, this induced an electric current radially outward from the center toward the rim. The current flowed out through the sliding spring contact m, through the external circuit, and back into the center of the disk through the axle.

4.
This large belt-driven high-current dynamo produced 310 amperes at 7 volts. Dynamos are no longer used due to the size and complexity of the commutator needed for high power applications.

Armature (electrical engineering)
–
The armature, in contrast, must carry current, so it is always a conductor or a conductive coil, oriented normal to both the field and to the direction of motion, torque, or force. The first is to carry current crossing the field, thus creating shaft torque in a machine or force in a linear machine. The second role is to generate an electromotive f

1.
A DC armature.

2.
Armature Reaction

Two-stroke engine
–
A two-stroke, or two-cycle, engine is a type of internal combustion engine which completes a power cycle with two strokes of the piston during only one crankshaft revolution. This is in contrast to an engine, which requires four strokes of the piston to complete a power cycle. In a two-stroke engine, the end of the combustion stroke, two-stroke eng

Heat exchanger
–
A heat exchanger is a device used to transfer heat between a solid object and a fluid, or between two or more fluids. The fluids may be separated by a wall to prevent mixing or they may be in direct contact. They are widely used in heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries,

1.
An interchangeable plate heat exchanger applied to the system of a swimming pool

4.
A heat exchanger in a steam power station contaminated with macrofouling.

Electric switchboard
–
An electric switchboard is a device that directs electricity from one or more sources of supply to several smaller regions of usage. It is an assembly of one or more panels, each of which contains switches that allow electricity to be redirected, in general, switchboards may distribute power to transformers, panelboards, control equipment, and, ult

1.
A modern electric switchboard

2.
Antique electrical switchboard, operational at a US plant in 2014. It features open style breakers, mounted on slabs of slate stone insulator.

Propeller shaft
–
As torque carriers, drive shafts are subject to torsion and shear stress, equivalent to the difference between the input torque and the load. They must therefore be enough to bear the stress, whilst avoiding too much additional weight as that would in turn increase their inertia. The term drive shaft first appeared during the mid 19th century, in S

Propeller
–
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the blade, and a fluid is accelerated behind the blade. Their disadvantages are higher mechanical complexity and higher cost, the principle employed in using a screw propeller is u

1.
Propeller on a modern mid-sized merchant vessel. The propeller rotates clockwise to propel the ship forward when viewed from astern (right of picture), the person in the picture has his hand on the propeller's trailing edge

4.
Smith's original 1836 patent for a screw propeller of two full turns. He would later revise the patent, reducing the length to one turn.

Compressors
–
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a type of gas compressor. Compressors are similar to pumps, both increase the pressure on a fluid and both can transport the fluid through a pipe, as gases are compressible, the compressor also reduces the volume of a gas. Liqui

1.
A small stationary high pressure breathing air compressor for filling scuba cylinders

2.
A single stage centrifugal compressor

3.
A motor-driven six-cylinder reciprocating compressor that can operate with two, four or six cylinders.

4.
A three-stage diaphragm compressor

Crank start
–
A starter is a device used to rotate an internal-combustion engine so as to initiate the engines operation under its own power. Starters can be electric, pneumatic, hydraulic, or in case of large engines. Internal-combustion engines are feedback systems, which, once started, rely on the inertia from each cycle to initiate the next cycle. In a four-

1.
An automobile starter motor (larger cylinder). The smaller object on top is a starter solenoid which controls power to the starter motor.

Diesel fuel
–
Diesel engines have found broad use as a result of higher thermodynamic efficiency and thus fuel efficiency. This is particularly noted where diesel engines are run at part-load, as their air supply is not throttled as in a petrol engine, to distinguish these types, petroleum-derived diesel is increasingly called petrodiesel. Ultra-low-sulfur diese

Barge
–
A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. Some barges are not self-propelled and must be towed or pushed by towboats, Barge is attested from 1300, from Old French barge, from Vulgar Latin barga. The word originally could refer to any small boat, the modern meaning arose around 1480, bark small ship

Galley (kitchen)
–
The galley is the compartment of a ship, train, or aircraft where food is cooked and prepared. It can also refer to a kitchen on a naval base. A galley is the kitchen aboard a vessel, usually laid out in an efficient typical style with longitudinal units and this makes the best use of the usually limited space aboard ships. It also caters for the r

1.
Galley of the Austrian passenger ship S.S. Africa on the Mediterranean Sea about 1905.

4.
Example of a Galley (kitchen) that has been hand fitted by a carpenter.

Hand pump
–
Hand pumps are manually operated pumps, they use human power and mechanical advantage to move fluids or air from one place to another. They are widely used in country in the world for a variety of industrial, marine, irrigation. Most hand pumps have plungers or reciprocating pistons, and are positive displacement, one sort of pump once common world

Electro-hydraulic system
–
In automobiles, power steering helps drivers steer by augmenting steering effort of the steering wheel. Power steering can also be engineered to provide some artificial feedback of forces acting on the steered wheels, hydraulic power steering systems for cars augment steering effort via an actuator, a hydraulic cylinder that is part of a servo syst

1.
A power steering fluid reservoir and pulley driven pump

Winch
–
A winch is a mechanical device that is used to pull in or let out or otherwise adjust the tension of a rope or wire rope. In its simplest form it consists of a spool and attached hand crank, in larger forms, winches stand at the heart of machines as diverse as tow trucks, steam shovels and elevators. The spool can also be called the winch drum, mor

2.
Modern self-tailing winch on a sailing boat. Here, the line winched is a jib or spinnakersheet which runs from the sail (upper left, not shown) to a block (lower right,not shown) and from there to the lower part of the winch. The handle is detachable to facilitate handling of the line.

3.
Example of winch designed for wakeboarding. These winches consist of a small four-cycle gasoline engine, clutch, and spool all housed inside of a steel frame. A rider is towed rapidly toward the winch as the rope winds around the spool.

Rudder
–
A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other conveyance that moves through a fluid medium. On an aircraft the rudder is used primarily to counter adverse yaw, a rudder operates by redirecting the fluid past the hull or fuselage, thus imparting a turning or yawing motion to the craft. In

Quercus alba
–
Quercus alba, the white oak, is one of the preeminent hardwoods of eastern and central North America. It is an oak, native to eastern and central North America and found from Minnesota, Ontario, Quebec. Specimens have been documented to be over 450 years old, although called a white oak, it is very unusual to find an individual specimen with white

Keel
–
On boats and ships, keel can refer to either of two parts, a structural element that sometimes resembles a fin and protrudes below a boat along the central line, or a hydrodynamic element. As the laying down of the keel is the step in the construction of a ship, in British. Only the ships launching is considered significant in its creation. The wor

2.
"The initials of Susan Ford Bales being welded into the keel of the aircraft carrier USS Gerald R. Ford (CVN 78) during a keel laying and authentication ceremony at Northrop Grumman Shipbuilding in Newport News."

Knee (construction)
–
In woodworking, a knee is a natural or cut, curved piece of wood. Knees, sometimes called ships knees, are a form of bracing in boat building. A knee rafter in carpentry is a bent rafter used to gain head room in an attic, wood is a highly anisotropic material. Because wood is strongest when loaded in tension or compression along the grain, for a k

1.
Knee timbers in boat building

Cypress
–
Cypress is the name applied to many plants in the cypress family Cupressaceae, which is a conifer of northern temperate regions. Most cypress species are trees, while a few are shrubs, the word cypress is derived from Old French cipres, which was imported from Latin cypressus the latinisation of the Greek κυπάρισσος. Species that are known as cypre

Douglas-fir
–
Pseudotsuga menziesii, commonly known as Douglas fir or Douglas-fir, is an evergreen conifer species native to western North America. The common name honors David Douglas, a Scottish botanist and collector who first reported the extraordinary nature, the common name is misleading since it is not a true fir, i. e. not a member of the genus Abies. Fo

1.
Douglas fir Pseudotsuga menziesii

2.
Coast Douglas fir cone, from a tree grown from seed collected by David Douglas

Pinus classification
–
Pinus, the Pines, is a genus of approximately 111 extant tree and shrub species. The genus is split into two subgenera, subgenus Pinus, and subgenus Strobus. Each of the subgenera have several sections based on chloroplast DNA sequencing. Older classifications split the genus into three subgenera – subgenus Pinus, subgenus Strobus, and subgenus Duc

1.
Pinus sylvestris

2.
Pinus roxburghii

3.
Pinus elliottii

4.
Pinus muricata

Gleditsia
–
Gleditsia /ɡlᵻˈdɪtsiə/ is a genus of trees in the family Fabaceae, subfamily Caesalpinioideae, native to North America and Asia. The Latin name commemorates Johann Gottlieb Gleditsch, director of the Berlin Botanical Garden, there are 12 species, Gleditsia amorphoides Taubert Gleditsia aquatica Marshall - Water locust Gleditsia australis F. B. Forb

1.
Gleditsia

Treenail

1.
Building the Naga Pelangi - fitting the first plank required aligning many treenails

1.
National Register of Historic Places
–
The National Register of Historic Places is the United States federal governments official list of districts, sites, buildings, structures, and objects deemed worthy of preservation. The passage of the National Historic Preservation Act in 1966 established the National Register, of the more than one million properties on the National Register,80,000 are listed individually. The remainder are contributing resources within historic districts, each year approximately 30,000 properties are added to the National Register as part of districts or by individual listings. For most of its history the National Register has been administered by the National Park Service and its goals are to help property owners and interest groups, such as the National Trust for Historic Preservation, coordinate, identify, and protect historic sites in the United States. While National Register listings are mostly symbolic, their recognition of significance provides some financial incentive to owners of listed properties, protection of the property is not guaranteed. During the nomination process, the property is evaluated in terms of the four criteria for inclusion on the National Register of Historic Places, the application of those criteria has been the subject of criticism by academics of history and preservation, as well as the public and politicians. Occasionally, historic sites outside the proper, but associated with the United States are also listed. Properties can be nominated in a variety of forms, including individual properties, historic districts, the Register categorizes general listings into one of five types of properties, district, site, structure, building, or object. National Register Historic Districts are defined geographical areas consisting of contributing and non-contributing properties, some properties are added automatically to the National Register when they become administered by the National Park Service. These include National Historic Landmarks, National Historic Sites, National Historical Parks, National Military Parks/Battlefields, National Memorials, on October 15,1966, the Historic Preservation Act created the National Register of Historic Places and the corresponding State Historic Preservation Offices. Initially, the National Register consisted of the National Historic Landmarks designated before the Registers creation, approval of the act, which was amended in 1980 and 1992, represented the first time the United States had a broad-based historic preservation policy. To administer the newly created National Register of Historic Places, the National Park Service of the U. S. Department of the Interior, hartzog, Jr. established an administrative division named the Office of Archeology and Historic Preservation. Hartzog charged OAHP with creating the National Register program mandated by the 1966 law, ernest Connally was the Offices first director. Within OAHP new divisions were created to deal with the National Register, the first official Keeper of the Register was William J. Murtagh, an architectural historian. During the Registers earliest years in the late 1960s and early 1970s, organization was lax and SHPOs were small, understaffed, and underfunded. A few years later in 1979, the NPS history programs affiliated with both the U. S. National Parks system and the National Register were categorized formally into two Assistant Directorates. Established were the Assistant Directorate for Archeology and Historic Preservation and the Assistant Directorate for Park Historic Preservation, from 1978 until 1981, the main agency for the National Register was the Heritage Conservation and Recreation Service of the United States Department of the Interior. In February 1983, the two assistant directorates were merged to promote efficiency and recognize the interdependency of their programs, jerry L. Rogers was selected to direct this newly merged associate directorate

2.
National Historic Landmark
–
A National Historic Landmark is a building, district, object, site, or structure that is officially recognized by the United States government for its outstanding historical significance. Of over 85,000 places listed on the countrys National Register of Historic Places, a National Historic Landmark District may include contributing properties that are buildings, structures, sites or objects, and it may include non-contributing properties. Contributing properties may or may not also be separately listed, prior to 1935, efforts to preserve cultural heritage of national importance were made by piecemeal efforts of the United States Congress. The first National Historic Site designation was made for the Salem Maritime National Historic Site on March 17,1938. In 1960, the National Park Service took on the administration of the data gathered under this legislation. Because listings often triggered local preservation laws, legislation in 1980 amended the procedures to require owner agreement to the designations. On October 9,1960,92 properties were announced as designated NHLs by Secretary of the Interior Fred A. Seaton, more than 2,500 NHLs have been designated. Most, but not all, are in the United States, there are NHLs in all 50 states and the District of Columbia. Three states account for nearly 25 percent of the nations NHLs, three cities within these states all separately have more NHLs than 40 of the 50 states. In fact, New York City alone has more NHLs than all but five states, Virginia, California, Pennsylvania, Massachusetts, there are 74 NHLs in the District of Columbia. Some NHLs are in U. S. commonwealths and territories, associated states, and foreign states. There are 15 in Puerto Rico, the Virgin Islands, and other U. S. commonwealths and territories,5 in U. S. -associated states such as Micronesia, over 100 ships or shipwrecks have been designated as NHLs. About half of the National Historic Landmarks are privately owned, the National Historic Landmarks Program relies on suggestions for new designations from the National Park Service, which also assists in maintaining the landmarks. A friends group of owners and managers, the National Historic Landmark Stewards Association, works to preserve, protect, if not already listed on the National Register of Historic Places, an NHL is automatically added to the Register upon designation. About three percent of Register listings are NHLs, american Water Landmark List of U. S

3.
Chelsea, Massachusetts
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Chelsea is a city in Suffolk County, Massachusetts, United States, directly across the Mystic River from the city of Boston. As of 2013, Chelsea had an population of 36,828. It is also the second most densely populated city in Massachusetts behind Somerville, with a total area of just 2.5 square miles, Chelsea is the smallest city in Massachusetts in terms of total area. Chelsea is a diverse, working-class community that contains a level of industrial activity. It is one of only three Massachusetts cities in which the majority of the population identifies as Hispanic or Latino, alongside Lawrence, after flirting with bankruptcy in the 1990s, the once-struggling industrial city has reversed a prolonged decline and in recent years has enjoyed sustained economic growth. There has also been significant office, retail and restaurant development throughout the city, the area of Chelsea was first called Winnisimmet by the Massachusett tribe, which once lived there. It was settled in 1624 by Samuel Maverick, whose palisaded trading post is considered the first permanent settlement by Boston Harbor, in 1635, Maverick sold all of Winnisimmet, except for his house and farm, to Richard Bellingham. The community remained part of Boston until it was set off and incorporated in 1739, when it was named after Chelsea, a neighborhood in London, England. In 1775, the Battle of Chelsea Creek was fought in the area, part of George Washingtons army was stationed in Chelsea during the Siege of Boston. On February 22,1841, part of Chelsea was annexed by Saugus, on March 19,1846, North Chelsea, which consists of present-day Revere and Winthrop was established as a separate town. Reincorporated as a city in 1857, Chelsea developed as an industrial center, as the century wore on, steam power began to overtake the age of the sail and industry in the town began to shift toward manufacturing. Factories making rubber and elastic goods, boots and shoes, stoves and it became home to the Chelsea Naval Hospital designed by Alexander Parris and home for soldiers. According to local records, Nathan Morse, the first Jewish resident of Chelsea, arrived in 1864. However, Chelsea was a destination for the great wave of Russian and Eastern European immigrants, especially Russian Jews. By 1910 the number of Jews had grown to 11,225, in the 1930s there were about 20,000 Jewish residents in Chelsea out of a total population of almost 46,000. Given the area of the city, Chelsea may well have had the most Jews per square mile of any city outside of New York City. On April 12,1908, nearly half the city was destroyed in the first of two fires that would devastate Chelsea in the 20th century. The fire left 18,000 people,56 percent of the population, despite the magnitude of the destruction, it would only take the city about two and a half years to rebuild and five years to surpass the extent of 1908s infrastructure

4.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation

Geographic coordinate system
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Longitude lines are perpendicular and latitude lines are parallel to the equator.

5.
Tugboat
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A tug is a boat or ship that maneuvers vessels by pushing or towing them. Tugboats are powerful for their size and strongly built, and some are ocean-going, some tugboats serve as icebreakers or salvage boats. Early tugboats had steam engines, but today most have diesel engines, many tugboats have firefighting monitors, allowing them to assist in firefighting, especially in harbors. Seagoing tugs fall into four categories, The standard seagoing tug with model bow that tows its payload on a hawser. The notch tug which can be secured in a notch at the stern of a specially designed barge and this configuration is dangerous to use with a barge which is in ballast or in a head- or following sea. Therefore, notch tugs are usually built with a towing winch and these units stay combined under virtually any sea conditions and the tugs usually have poor sea-keeping designs for navigation without their barges attached. Vessels in this category are considered to be ships rather than tugboats. These vessels must show navigation lights compliant with those required of ships rather than required of tugboats. Articulated tug and barge units also utilize mechanical means to connect to their barges, the tug slips into a notch in the stern and is attached by a hinged connection. ATBs generally utilize Intercon and Bludworth connecting systems, aTBs are generally staffed as a large tugboat, with between seven and nine crew members. The typical American ATB operating on the east coast customarily displays navigational lights of a towing vessel pushing ahead, compared to seagoing tugboats, harbour tugboats are generally smaller and their width-to-length ratio is often higher, due to the need for a lower draught. In smaller harbours these are also termed lunch bucket boats, because they are only manned when needed and only at a minimum. The number of tugboats in a harbour varies with the harbour infrastructure, things to take into consideration includes ships with/without bow thrusters and forces like wind, current and waves and types of ship. River tugs are also referred to as towboats or pushboats and their hull designs would make open ocean operation dangerous. River tugs usually do not have any significant hawser or winch and their hulls feature a flat front or bow to line up with the rectangular stern of the barge, often with large pushing knees. Tugboat engines typically produce 500 to 2,500 kW, for safety, tugboats engines often feature two of each critical part for redundancy. A tugboats power is stated by its engines horsepower and its overall bollard pull. The largest commercial harbour tugboats in the 2000s-2010s, used for towing container ships or similar, had around 60-65 tons of bollard pull, Tugboats are highly maneuverable, and various propulsion systems have been developed to increase maneuverability and increase safety

6.
Boston
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Boston is the capital and most populous city of the Commonwealth of Massachusetts in the United States. Boston is also the seat of Suffolk County, although the county government was disbanded on July 1,1999. The city proper covers 48 square miles with a population of 667,137 in 2015, making it the largest city in New England. Alternately, as a Combined Statistical Area, this wider commuting region is home to some 8.1 million people, One of the oldest cities in the United States, Boston was founded on the Shawmut Peninsula in 1630 by Puritan settlers from England. It was the scene of several key events of the American Revolution, such as the Boston Massacre, the Boston Tea Party, the Battle of Bunker Hill, and the Siege of Boston. Upon U. S. independence from Great Britain, it continued to be an important port and manufacturing hub as well as a center for education, through land reclamation and municipal annexation, Boston has expanded beyond the original peninsula. Its rich history attracts many tourists, with Faneuil Hall alone drawing over 20 million visitors per year, Bostons many firsts include the United States first public school, Boston Latin School, first subway system, the Tremont Street Subway, and first public park, Boston Common. Bostons economic base also includes finance, professional and business services, biotechnology, information technology, the city has one of the highest costs of living in the United States as it has undergone gentrification, though it remains high on world livability rankings. Bostons early European settlers had first called the area Trimountaine but later renamed it Boston after Boston, Lincolnshire, England, the renaming on September 7,1630 was by Puritan colonists from England who had moved over from Charlestown earlier that year in quest of fresh water. Their settlement was limited to the Shawmut Peninsula, at that time surrounded by the Massachusetts Bay and Charles River. The peninsula is thought to have been inhabited as early as 5000 BC, in 1629, the Massachusetts Bay Colonys first governor John Winthrop led the signing of the Cambridge Agreement, a key founding document of the city. Puritan ethics and their focus on education influenced its early history, over the next 130 years, the city participated in four French and Indian Wars, until the British defeated the French and their Indian allies in North America. Boston was the largest town in British America until Philadelphia grew larger in the mid-18th century, Bostons harbor activity was significantly curtailed by the Embargo Act of 1807 and the War of 1812. Foreign trade returned after these hostilities, but Bostons merchants had found alternatives for their investments in the interim. Manufacturing became an important component of the economy, and the citys industrial manufacturing overtook international trade in economic importance by the mid-19th century. Boston remained one of the nations largest manufacturing centers until the early 20th century, a network of small rivers bordering the city and connecting it to the surrounding region facilitated shipment of goods and led to a proliferation of mills and factories. Later, a network of railroads furthered the regions industry. Boston was a port of the Atlantic triangular slave trade in the New England colonies

7.
Thomas Edison
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Thomas Alva Edison was an American inventor and businessman, who has been described as Americas greatest inventor. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and the long-lasting, practical electric light bulb. Edison was an inventor, holding 1,093 US patents in his name, as well as many patents in the United Kingdom, France. Edisons inventions contributed to mass communication and, in particular, telecommunications and these included a stock ticker, a mechanical vote recorder, a battery for an electric car, electrical power, recorded music and motion pictures. His advanced work in these fields was an outgrowth of his career as a telegraph operator. Edison developed a system of generation and distribution to homes, businesses. His first power station was on Pearl Street in Manhattan, New York, Thomas Edison was born in Milan, Ohio, and grew up in Port Huron, Michigan. He was the seventh and last child of Samuel Ogden Edison, Jr. and Nancy Matthews Elliott. His father, the son of a Loyalist refugee, had moved as a boy with the family from Nova Scotia, settling in southwestern Ontario, in a known as Shewsbury, later Vienna. Samuel Jr. eventually fled Ontario because he took part in the unsuccessful Mackenzie Rebellion of 1837 and his father, Samuel Sr. had earlier fought in the War of 1812 as captain of the First Middlesex Regiment. By contrast, Samuel Jr. s struggle found him on the losing side, once across the border, he found his way to Milan, Ohio. His patrilineal family line was Dutch by way of New Jersey and his mother taught him at home. Much of his education came from reading R. G, parkers School of Natural Philosophy and The Cooper Union for the Advancement of Science and Art. Edison developed hearing problems at an early age, the cause of his deafness has been attributed to a bout of scarlet fever during childhood and recurring untreated middle-ear infections. In his later years, he modified the story to say the injury occurred when the conductor, in helping him onto a moving train, Edisons family moved to Port Huron, Michigan, after the railroad bypassed Milan in 1854 and business declined. Edison sold candy and newspapers on trains running from Port Huron to Detroit and he briefly worked as a telegraph operator in 1863 for the Grand Trunk Railway at Stratford, Ontario railway at age 16. He was held responsible for a near collision and he also studied qualitative analysis and conducted chemical experiments on the train until he left the job. Edison obtained the right to sell newspapers on the road, and, with the aid of four assistants, he set in type and printed the Grand Trunk Herald

8.
General Electric
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General Electric, often abbreviated as GE, is an American multinational conglomerate corporation incorporated in New York and headquartered in Boston, Massachusetts. In 2011, GE ranked among the Fortune 500 as the 68th-largest firm in the U. S. by gross revenue, as of 2012, the company was listed the fourth-largest in the world among the Forbes Global 2000, further metrics being taken into account. The Nobel Prize has twice been awarded to employees of General Electric, Irving Langmuir in 1932, on January 13,2016, it was announced that GE will be moving its corporate headquarters from Fairfield, Connecticut to the South Boston Waterfront neighborhood of Boston, Massachusetts. The first group of workers arrived in the summer of 2016, morgan and the Vanderbilt family for Edisons lighting experiments. The new company also acquired Sprague Electric Railway & Motor Company in the same year, both plants continue to operate under the GE banner to this day. The company was incorporated in New York, with the Schenectady plant used as headquarters for years thereafter. Around the same time, General Electrics Canadian counterpart, Canadian General Electric, was formed, in 1896, General Electric was one of the original 12 companies listed on the newly formed Dow Jones Industrial Average. After 120 years, it is the one of the original companies still listed on the Dow index. In 1911, General Electric absorbed the National Electric Lamp Association into its lighting business, GE established its lighting division headquarters at Nela Park in East Cleveland, Ohio. Nela Park is still the headquarters for GEs lighting business, owen D. Young, through GE, founded the Radio Corporation of America in 1919 to further international radio. GE used RCA as its retail arm for radio sales from 1919, in 1927, Ernst Alexanderson of GE made the first demonstration of his television broadcasts at his General Electric Realty Plot home at 1132 Adams Rd, Schenectady, NY. The sound was broadcast on GEs WGY, experimental television station W2XAD evolved into station WRGB which—along with WGY and WGFM —was owned and operated by General Electric until 1983. GEs history of working with turbines in the field gave them the engineering know-how to move into the new field of aircraft turbosuperchargers. Led by Sanford Alexander Moss, GE introduced the first superchargers during World War I, superchargers became indispensable in the years immediately prior to World War II, and GE was the world leader in exhaust-driven supercharging when the war started. This experience, in turn, made GE a natural selection to develop the Whittle W.1 jet engine that was demonstrated in the United States in 1941, GE ranked ninth among United States corporations in the value of wartime production contracts. In 2002, GE acquired the assets of Enron during its bankruptcy proceedings. Some consumers boycotted GE light bulbs, refrigerators and other products in the 1980s and 1990s to protest GEs role in weapons production. With IBM, Burroughs, NCR, Control Data Corporation, Honeywell, RCA and UNIVAC, GE had a line of general purpose and special purpose computers

General Electric
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General Electric in Schenectady, NY, aerial view, 1896
General Electric
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General Electric Company
General Electric
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Plan of Schenectady plant, 1896
General Electric
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A 23-ton diesel-electric locomotive made at the General Electric Corp. plant in Schenectady, New York

9.
Solomons, Maryland
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Solomons, also known as Solomons Island, is an unincorporated community and census-designated place in Calvert County, Maryland, United States. The population was 2,368 at the 2010 census, up from 1,536 at the 2000 census, Solomons is a popular weekend destination spot in the Baltimore–Washington metropolitan area. Solomons is located at the tip of Calvert County at 38°20′11″N 76°27′51″W. It includes Solomons Island and mainland on the side of the mouth of Patuxent River. It is just across from the U. S. Patuxent River Naval Air Station, the climate in this area is characterized by hot, humid summers and generally mild to cool winters. According to the Köppen Climate Classification system, Solomons has a subtropical climate. Originally called Bournes Island, then Somervells Island, Solomons takes its name from 19th century Baltimore businessman Isaac Solomon, Solomons home still stands on the front of the island. The area has been inhabited since colonial times, in the 19th century, shipyards developed to support the islands fishing fleet. The Marsh Shipyard built schooners and sloops but became famous for its bugeyes, in the War of 1812, Commodore Joshua Barneys flotilla sailed from here to attack British vessels on Chesapeake Bay. The deep, protected harbor has been a busy marine center ever since, during World War II, the island was chosen by the Allied command as the site for training amphibious invasion forces. The lessons learned at Solomons proved invaluable on D-Day, at Tarawa, at Guadalcanal, three naval bases were established at the mouth of the Patuxent River. These three facilities made a contribution to the war effort and brought new jobs to local residents. Between 1942 and 1945, the population of Solomons increased from 263 to more than 2,600, over 60,000 troops trained at Solomons during the war. Coincidentally, many of the servicemen who trained at the Solomons base in Maryland were sent to fight in the Solomon Islands in the Pacific Ocean, Solomons was the site of the following U. S. The bridge leads from just off Solomons Island proper to St. Marys County, Solomons also has three major hotels, a U. S. Navy family recreation center, and a church retirement home. St. Peters Chapel is an historic 1889 Carpenter Gothic-style church that is still in use, most sculptures are on loan from the National Gallery of Art or the Hirshhorn Museum. During the warm season, water pumped through concealed ductwork emerges and cascades out of the tongs jaws, the fallen water pools around the boat in a map-shaped decorative basin where sometimes visiting children splash their feet. Since 1993, Annmarie Garden has hosted a national juried arts festival at which typically around 100 traveling artists encamp in display tents for a weekend to sell their wares

10.
Salem, Massachusetts
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Salem is a coastal city in Essex County, Massachusetts, in the United States, located on Massachusetts North Shore. It is a New England bedrock of history and is considered one of the most significant seaports in Puritan American history, the citys reported population was 41,340 at the 2010 census. Salem and Lawrence are the county seats of Essex County, though the county government was abolished in 1999, much of the citys cultural identity reflects its role as the location of the Salem witch trials of 1692, as featured in Arthur Millers The Crucible. Tourists know Salem as a mix of important historical sites and a vibrant downtown that has more than 60 restaurants, cafes, in 2012, the Retailers Association of Massachusetts chose Salem for their inaugural Best Shopping District award. President Barack Obama signed executive order HR1339 on January 10,2013, more than one million tourists from all around the world visit Salem annually, bringing in at least $100 million in tourism spending each year. More than 250,000 visited Salem over Halloween weekend in 2016, Salem is located at the mouth of the Naumkeag river at the site of an ancient American Indian village and trading center. It was first settled by Europeans in 1626, when a company of fishermen arrived from Cape Ann, led by Roger Conant. Conants leadership provided the stability to survive the first two years, but he was replaced by John Endecott, one of the new arrivals, Conant graciously stepped aside and was granted 200 acres of land in compensation. These New Planters and the Old Planters agreed to cooperate, in part due to the diplomacy of Conant. In 1628, Endecott ordered that the Great House be moved from Cape Ann, when Higginson arrived in Salem, he wrote that we found a faire house newly built for the Governor which was remarkable for being two stories high. A year later, the Massachusetts Bay Charter was issued creating the Massachusetts Bay Colony with Matthew Craddock as its governor in London, John Winthrop was elected Governor in late 1629, and arrived with the Winthrop Fleet in 1630, beginning the Great Migration. In 1639, Endecotts was one of the signatures on the contract for enlarging the meeting house in Town House Square for the First Church in Salem. This document remains part of the records at City Hall. He was active in the affairs of the town throughout his life, Samuel Skelton was the first pastor of the First Church of Salem, which is the original Puritan church in North America. Endecott already had a relationship with Skelton, having been converted by him. Roger Conant died in 1679 at the age of 87, a statue commemorating him stands overlooking Salem Common. Salem originally included much of the North Shore, including Marblehead, most of the accused in the Salem witch trials lived in nearby Salem Village, now known as Danvers, although a few lived on the outskirts of Salem. Salem Village also included Peabody and parts of present-day Beverly, Middleton, Topsfield, Wenham, and Manchester-by-the-Sea were once parts of Salem

11.
Plymouth, Massachusetts
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Plymouth /ˈplɪməθ/ is a town in Plymouth County, Massachusetts, United States. Plymouth holds a place of prominence in American history, folklore, and culture. Plymouth was the site of the founded in 1620 by the Pilgrims. Plymouth is where New England was first established and it is the oldest municipality in New England and one of the oldest in the United States. The town has served as the location of prominent events. Plymouth served as the capital of Plymouth Colony from its founding in 1620 until the merger with the Massachusetts Bay colony in 1691. Plymouth is named after the English city of the same name, Plymouth is the largest municipality in Massachusetts by area. The population is 58,271, according to the 2014 Demographics by Cubit, Plymouth is one of two county seats of Plymouth County, the other being Brockton. Plymouth is located approximately 40 miles south of Boston in a region of Massachusetts known as the South Shore. Throughout the 19th century, the town thrived as a center of ropemaking, fishing, and shipping, and once held the worlds largest ropemaking company and it continues to be an active port, but today the major industry of Plymouth is tourism. Plymouth is served by Plymouth Municipal Airport, and contains Pilgrim Hall Museum, as one of the countrys first settlements, Plymouth is well known in the United States for its historical value. The events surrounding the history of Plymouth have become part of the ethos of the United States, particularly relating to Plymouth Rock, the Pilgrims. The town itself is a popular tourist spot during the Thanksgiving holiday, Plymouth is home to the Old Colony Club, one of the oldest Gentlemens clubs in the world. Prior to the arrival of the Pilgrims, the location of Plymouth was a village of 2,000 Wampanoag Native Americans called Patuxet and this region that became Plymouth was visited twice by European explorers prior to the establishment of Plymouth Colony. In 1605, Samuel de Champlain sailed to Plymouth Harbor, calling it Port St. Louis, captain John Smith, a leader of the colony at Jamestown, Virginia, explored parts of Cape Cod Bay, he is credited with naming the region New Plimouth. Two plagues afflicted coastal New England in 1614 and 1617, possibly transmitted from British, the plague killed between 90% and 95% of the local Wampanoag inhabitants. Plymouth has played an important role in American colonial history. It was the landing site of the first voyage of the Mayflower

12.
Mystic River
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The Mystic River is a 7. 0-mile-long river in Massachusetts, in the United States. Its name derives from the Wampanoag word muhs-uhtuq, which translates to big river, in an Algonquian language, Missi-Tuk means a great river whose waters are driven by waves, alluding to the original tidal nature of the Mystic. It lies to the north of and flows parallel to the lower portions of the Charles River. The Mystic River has a history of industrial use and a continuing water quality problem. The river joins the Charles River to form inner Boston Harbor and its watershed contains 44 lakes and ponds, the largest of which is Spot Pond in the Middlesex Fells, with an area of 307 acres. Before recorded history, Native Americans and then later colonists used weirs to catch alewives, in 1631, after the arrival of the English, the first ship built by Europeans in Massachusetts, the Blessing of the Bay, was launched from the rivers shores. A few years later the first bridge was built, neighboring towns squabbled about the costs for more than a hundred years. In 1775, the Battle of Chelsea Creek took place in the watershed in May. In 1805 the Middlesex Canal linked the Charles and Mystic Rivers to the Merrimack River in Lowell, shipbuilding peaked in the 1840s as schooners and sloops transported timber and molasses for rum distilleries between Medford and the West Indies. By 1865, overfishing and pollution all but eliminated commercial fishing, extensive salt marshes lined the banks of the Mystic until 1909, when the first dam was built across the river, converting salt marsh to freshwater marsh and enabling development. A dam named for Amelia Earhart, was built in 1966 and it has three locks to allow the passage of boats, and is equipped with pumps to push fresh water out to the harbor even during high tide. Dam operators leave the open at times to allow the passage of fish. There is a ladder, but it has never been functional. The dam is closed to the public, in 1950, construction was completed on the Maurice J. Tobin Bridge which spans the Mystic River, joining Charlestown and Chelsea. Although most of species still live in the Mystic River, pollution. Pollution came from various mills and a ship building yard in the past. The main source of pollution in the 20th century and into the present is from drainage from cities, many of the records of nearby drainage pipes have been lost, or have undocumented changes and diversions. Once described as having so many herring that one could cross the river on their backs, pollution has raised bacteria levels and turbidity, making it unfavorable for fish to live in

Mystic River
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A quiet afternoon on the Mystic River, as seen from very close to Grandfather's House, Medford, Massachusetts
Mystic River
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Engraving of the Mystic River and environs in 1790
Mystic River
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A 1903 USGS map of the Mystic River and environs
Mystic River
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Mystic River as seen from the Cradock Bridge

13.
Charles River
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The Charles River is an 80 mi long river in eastern Massachusetts. From its source in Hopkinton the river flows in a direction, traveling through 23 cities. Thirty-three lakes and ponds and 35 municipalities are entirely or partially part of the Charles River drainage basin, despite the rivers length and relatively large drainage area, its source is only 26 miles from its mouth, and the river drops only 350 feet from source to sea. The Charles River watershed contains more than 8,000 acres of protected wetlands and these areas are important in preventing downstream flooding and providing natural habitats to native species. Brandeis University, Harvard University, Boston University, and the Massachusetts Institute of Technology are located along the Charles River, near its mouth, it forms the border between downtown Boston and Cambridge and Charlestown. The river opens into a basin and is lined by the parks of the Charles River Reservation. On the Charles River Esplanade stands the Hatch Shell, where concerts are given in summer evenings, the basin is especially known for its Independence Day celebration. The river is known for its rowing, sculling, dragonboating. The river may also be kayaked, depending on the season, however, kayakers can only navigate the Charles by getting out, the Lower Basin between the Longfellow and Harvard bridges is home to Community Boating, the Harvard University Sailing Center, and the MIT Sailing Pavilion. The Head of the Charles Regatta is held here every October, in early June, the annual Hong Kong Boston Dragon boat Festival is held in Cambridge, near the Weeks Footbridge. The Charles River Bike Path runs 23 miles along the banks of the Charles, starting at the Museum of Science and passing the campuses of MIT, Harvard, the path is popular with runners and bikers. Many runners gauge their distance and speed by keeping track of the mileage between the bridges along the route, for several years, the Charles River Speedway operated along part of the river. On July 13,2013, swimming for the public was permitted for the first time in more than 50 years. The rivers name, preceding the English version, was thought to be Quinobequin, though that attribution has been discredited by, among others. The river was used by Native Americans for local transportation and fishing, when Smith presented his map to Charles I he suggested that the king should feel free to change any of the barbarous names for English ones. The king made such changes, but only four survive today. In portions of its length, the Charles drops slowly in elevation and has relatively little current, despite this, early settlers in Dedham, Massachusetts, found a way to use the Charles to power mills. In 1639, the town dug a canal from the Charles to a brook that drained to the Neponset River

14.
Fort Point Channel
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Fort Point Channel is a maritime channel separating South Boston from downtown Boston, Massachusetts, feeding into Boston Harbor. The south part of it has gradually filled in for use by the South Bay rail yard. At its south end, the channel once widened into South Bay, the Boston Tea Party occurred at its northern end. The channel is surrounded by the Fort Point neighborhood, which is named after the same colonial-era fort. The banks of the channel are still busy with activity, South of Summer Street on the west side of the channel is a large United States Postal Service facility. A large parcel, home to Gillette, lies at the southeast corner of the channel. The back of the Federal Reserve Bank of Boston looks over the channel, and another federal building, one of Bostons odder attractions, the Hood Milk Bottle, lies on the banks as well, next to Boston Childrens Museum. During the 1980s, a nightclub and popular concert venue called The Channel was located on the South Boston bank, on October 21,2011, Fort Point Pier opened for public use south of the Summer Street Bridge. To prepare for construction, a section of the Fort Point Channel seawall south of Necco Court was restored by P&G Gillette. Public access has made Fort Point Channel popular for kayaking and standup paddle boarding

Fort Point Channel
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Fort Point Channel, as seen from the south end looking north.
Fort Point Channel
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Fort Point Channel
Fort Point Channel
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Old Northern Avenue Bridge
Fort Point Channel
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Fort Point as it relates to how Boston was filled in.

15.
Maine
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Maine is the northernmost state in the New England region of the northeastern United States. Maine is the 39th most extensive and the 41st most populous of the U. S. states and territories and it is bordered by New Hampshire to the west, the Atlantic Ocean to the east, and the Canadian provinces of New Brunswick and Quebec to the north. Maine is the easternmost state in the contiguous United States, and it is known for its jagged, rocky coastline, low, rolling mountains, heavily forested interior, and picturesque waterways, and also its seafood cuisine, especially clams and lobster. There is a continental climate throughout the state, even in areas such as its most populous city of Portland. For thousands of years, indigenous peoples were the inhabitants of the territory that is now Maine. At the time of European arrival in what is now Maine, the first European settlement in the area was by the French in 1604 on Saint Croix Island, by Pierre Dugua, Sieur de Mons. The first English settlement was the short-lived Popham Colony, established by the Plymouth Company in 1607, as Maine entered the 18th century, only a half dozen European settlements had survived. Loyalist and Patriot forces contended for Maines territory during the American Revolution, Maine was part of the Commonwealth of Massachusetts until 1820, when it voted to secede from Massachusetts to become an independent state. On March 15,1820, it was admitted to the Union as the 23rd state under the Missouri Compromise, there is no definitive explanation for the origin of the name Maine, but the most likely origin is the name given by early explorers after a province in France. Whatever the origin, the name was fixed for English settlers in 1665 when the English Kings Commissioners ordered that the Province of Maine be entered from then on in official records. The state legislature in 2001 adopted a resolution establishing Franco-American Day, other theories mention earlier places with similar names, or claim it is a nautical reference to the mainland. Attempts to uncover the history of the name of Maine began with James Sullivans 1795 History of the District of Maine. He made the allegation that the Province of Maine was a compliment to the queen of Charles I, Henrietta Maria. MAINE appears in the Domesday Book of 1086 in reference to the county of Dorset, the view generally held among British place name scholars is that Mayne in Dorset is Brythonic, corresponding to modern Welsh maen, plural main or meini. Some early spellings are, MAINE1086, MEINE1200, MEINES1204, mason had served with the Royal Navy in the Orkney Islands where the chief island is called Mainland, a possible name derivation for these English sailors. Initially, several tracts along the coast of New England were referred to as Main or Maine, Maine is the only state whose name has exactly one syllable. The original inhabitants of the territory that is now Maine were Algonquian-speaking Wabanaki peoples, including the Abenaki, Passamaquoddy, Maliseet and Penobscot, who had a loose confederacy. European contact with what is now called Maine started around 1200 CE when Norwegians interacted with the native Penobscot in present-day Hancock County, most likely through trade

16.
New York (state)
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New York is a state in the northeastern United States, and is the 27th-most extensive, fourth-most populous, and seventh-most densely populated U. S. state. New York is bordered by New Jersey and Pennsylvania to the south and Connecticut, Massachusetts, and Vermont to the east. With an estimated population of 8.55 million in 2015, New York City is the most populous city in the United States, the New York Metropolitan Area is one of the most populous urban agglomerations in the world. New York City makes up over 40% of the population of New York State, two-thirds of the states population lives in the New York City Metropolitan Area, and nearly 40% lives on Long Island. Both the state and New York City were named for the 17th-century Duke of York, the next four most populous cities in the state are Buffalo, Rochester, Yonkers, and Syracuse, while the state capital is Albany. New York has a diverse geography and these more mountainous regions are bisected by two major river valleys—the north-south Hudson River Valley and the east-west Mohawk River Valley, which forms the core of the Erie Canal. Western New York is considered part of the Great Lakes Region and straddles Lake Ontario, between the two lakes lies Niagara Falls. The central part of the state is dominated by the Finger Lakes, New York had been inhabited by tribes of Algonquian and Iroquoian-speaking Native Americans for several hundred years by the time the earliest Europeans came to New York. The first Europeans to arrive were French colonists and Jesuit missionaries who arrived southward from settlements at Montreal for trade, the British annexed the colony from the Dutch in 1664. The borders of the British colony, the Province of New York, were similar to those of the present-day state, New York is home to the Statue of Liberty, a symbol of the United States and its ideals of freedom, democracy, and opportunity. In the 21st century, New York has emerged as a node of creativity and entrepreneurship, social tolerance. On April 17,1524 Verrazanno entered New York Bay, by way of the now called the Narrows into the northern bay which he named Santa Margherita. Verrazzano described it as a vast coastline with a delta in which every kind of ship could pass and he adds. This vast sheet of water swarmed with native boats and he landed on the tip of Manhattan and possibly on the furthest point of Long Island. Verrazannos stay was interrupted by a storm which pushed him north towards Marthas Vineyard, in 1540 French traders from New France built a chateau on Castle Island, within present-day Albany, due to flooding, it was abandoned the next year. In 1614, the Dutch under the command of Hendrick Corstiaensen, rebuilt the French chateau, Fort Nassau was the first Dutch settlement in North America, and was located along the Hudson River, also within present-day Albany. The small fort served as a trading post and warehouse, located on the Hudson River flood plain, the rudimentary fort was washed away by flooding in 1617, and abandoned for good after Fort Orange was built nearby in 1623. Henry Hudsons 1609 voyage marked the beginning of European involvement with the area, sailing for the Dutch East India Company and looking for a passage to Asia, he entered the Upper New York Bay on September 11 of that year

17.
World War II
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World War II, also known as the Second World War, was a global war that lasted from 1939 to 1945, although related conflicts began earlier. It involved the vast majority of the worlds countries—including all of the great powers—eventually forming two opposing alliances, the Allies and the Axis. It was the most widespread war in history, and directly involved more than 100 million people from over 30 countries. Marked by mass deaths of civilians, including the Holocaust and the bombing of industrial and population centres. These made World War II the deadliest conflict in human history, from late 1939 to early 1941, in a series of campaigns and treaties, Germany conquered or controlled much of continental Europe, and formed the Axis alliance with Italy and Japan. Under the Molotov–Ribbentrop Pact of August 1939, Germany and the Soviet Union partitioned and annexed territories of their European neighbours, Poland, Finland, Romania and the Baltic states. In December 1941, Japan attacked the United States and European colonies in the Pacific Ocean, and quickly conquered much of the Western Pacific. The Axis advance halted in 1942 when Japan lost the critical Battle of Midway, near Hawaii, in 1944, the Western Allies invaded German-occupied France, while the Soviet Union regained all of its territorial losses and invaded Germany and its allies. During 1944 and 1945 the Japanese suffered major reverses in mainland Asia in South Central China and Burma, while the Allies crippled the Japanese Navy, thus ended the war in Asia, cementing the total victory of the Allies. World War II altered the political alignment and social structure of the world, the United Nations was established to foster international co-operation and prevent future conflicts. The victorious great powers—the United States, the Soviet Union, China, the United Kingdom, the Soviet Union and the United States emerged as rival superpowers, setting the stage for the Cold War, which lasted for the next 46 years. Meanwhile, the influence of European great powers waned, while the decolonisation of Asia, most countries whose industries had been damaged moved towards economic recovery. Political integration, especially in Europe, emerged as an effort to end pre-war enmities, the start of the war in Europe is generally held to be 1 September 1939, beginning with the German invasion of Poland, Britain and France declared war on Germany two days later. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937, or even the Japanese invasion of Manchuria on 19 September 1931. Others follow the British historian A. J. P. Taylor, who held that the Sino-Japanese War and war in Europe and its colonies occurred simultaneously and this article uses the conventional dating. Other starting dates sometimes used for World War II include the Italian invasion of Abyssinia on 3 October 1935. The British historian Antony Beevor views the beginning of World War II as the Battles of Khalkhin Gol fought between Japan and the forces of Mongolia and the Soviet Union from May to September 1939, the exact date of the wars end is also not universally agreed upon. It was generally accepted at the time that the war ended with the armistice of 14 August 1945, rather than the formal surrender of Japan

18.
US Navy
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The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U. S. Navy is the largest, most capable navy in the world, the U. S. Navy has the worlds largest aircraft carrier fleet, with ten in service, two in the reserve fleet, and three new carriers under construction. The service has 323,792 personnel on duty and 108,515 in the Navy Reserve. It has 274 deployable combat vessels and more than 3,700 operational aircraft as of October 2016, the U. S. Navy traces its origins to the Continental Navy, which was established during the American Revolutionary War and was effectively disbanded as a separate entity shortly thereafter. It played a role in the American Civil War by blockading the Confederacy. It played the role in the World War II defeat of Imperial Japan. The 21st century U. S. Navy maintains a global presence, deploying in strength in such areas as the Western Pacific, the Mediterranean. The Navy is administratively managed by the Department of the Navy, the Department of the Navy is itself a division of the Department of Defense, which is headed by the Secretary of Defense. The Chief of Naval Operations is an admiral and the senior naval officer of the Department of the Navy. The CNO may not be the highest ranking officer in the armed forces if the Chairman or the Vice Chairman of the Joint Chiefs of Staff. The mission of the Navy is to maintain, train and equip combat-ready Naval forces capable of winning wars, deterring aggression, the United States Navy is a seaborne branch of the military of the United States. The Navys three primary areas of responsibility, The preparation of naval forces necessary for the prosecution of war. The development of aircraft, weapons, tactics, technique, organization, U. S. Navy training manuals state that the mission of the U. S. Armed Forces is to prepare and conduct prompt and sustained combat operations in support of the national interest, as part of that establishment, the U. S. Navys functions comprise sea control, power projection and nuclear deterrence, in addition to sealift duties. It follows then as certain as that night succeeds the day, that without a decisive naval force we can do nothing definitive, the Navy was rooted in the colonial seafaring tradition, which produced a large community of sailors, captains, and shipbuilders. In the early stages of the American Revolutionary War, Massachusetts had its own Massachusetts Naval Militia, the establishment of a national navy was an issue of debate among the members of the Second Continental Congress. Supporters argued that a navy would protect shipping, defend the coast, detractors countered that challenging the British Royal Navy, then the worlds preeminent naval power, was a foolish undertaking. Commander in Chief George Washington resolved the debate when he commissioned the ocean-going schooner USS Hannah to interdict British merchant ships, and reported the captures to the Congress

19.
US Army
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The United States Army is the largest branch of the United States Armed Forces and performs land-based military operations. After the Revolutionary War, the Congress of the Confederation created the United States Army on 3 June 1784, the United States Army considers itself descended from the Continental Army, and dates its institutional inception from the origin of that armed force in 1775. As a uniformed service, the Army is part of the Department of the Army. As a branch of the forces, the mission of the U. S. The branch participates in conflicts worldwide and is the major ground-based offensive and defensive force of the United States, the United States Army serves as the land-based branch of the U. S. Section 3062 of Title 10, U. S, the army was initially led by men who had served in the British Army or colonial militias and who brought much of British military heritage with them. As the Revolutionary War progressed, French aid, resources, a number of European soldiers came on their own to help, such as Friedrich Wilhelm von Steuben, who taught Prussian Army tactics and organizational skills. The army fought numerous pitched battles and in the South in 1780–81 sometimes used the Fabian strategy and hit-and-run tactics, hitting where the British were weakest, to wear down their forces. Washington led victories against the British at Trenton and Princeton, but lost a series of battles in the New York and New Jersey campaign in 1776, with a decisive victory at Yorktown, and the help of the French, the Continental Army prevailed against the British. After the war, though, the Continental Army was quickly given land certificates, State militias became the new nations sole ground army, with the exception of a regiment to guard the Western Frontier and one battery of artillery guarding West Points arsenal. However, because of continuing conflict with Native Americans, it was realized that it was necessary to field a trained standing army. The War of 1812, the second and last war between the United States and Great Britain, had mixed results. After taking control of Lake Erie in 1813, the U. S. Army seized parts of western Upper Canada, burned York and defeated Tecumseh, which caused his Western Confederacy to collapse. Following U. S. victories in the Canadian province of Upper Canada, British troops, were able to capture and burn Washington, which was defended by militia, in 1814. Two weeks after a treaty was signed, Andrew Jackson defeated the British in the Battle of New Orleans and Siege of Fort St. Philip, U. S. troops and sailors captured HMS Cyane, Levant, and Penguin in the final engagements of the war. Per the treaty, both sides, the United States and Great Britain, returned to the status quo. Both navies kept the warships they had seized during the conflict, the armys major campaign against the Indians was fought in Florida against Seminoles. It took long wars to defeat the Seminoles and move them to Oklahoma

20.
Bath, Maine
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Bath is a city in Sagadahoc County, Maine, in the United States. The population was 8,514 at the 2010 census, and 8,357 as of 2013 and it is the county seat of Sagadahoc County, Which includes one city and 10 towns. The city is popular with tourists, many drawn by its 19th-century architecture and it is home to the Bath Iron Works and Heritage Days Festival, held annually on the Fourth of July weekend. It is commonly known as The City of Ships, Bath is part of the metropolitan statistical area of Greater Portland. Abenaki Indians called the area Sagadahoc, meaning mouth of big river and it was a reference to the Kennebec River, which Samuel de Champlain explored in 1605. Popham Colony was established in 1607 downstream, together with Fort St George, the settlement failed due to harsh weather and lack of leadership, but the colonists built the New Worlds first oceangoing vessel constructed by English shipwrights, the Virginia of Sagadahoc. It provided passage back to England, most of Bath, Maine, was settled by travelers from Bath, England. The next settlement at Sagadahoc was about 1660, when the land was taken from an Indian sagamore known as Robinhood, incorporated as part of Georgetown in 1753, Bath was set off and incorporated as a town on February 17,1781. It was named by the postmaster, Dummer Sewell, after Bath in Somerset, in 1844, a portion of the town was set off to create West Bath. On June 14,1847, Bath was incorporated as a city, Land was annexed from West Bath in 1855. Several industries developed in the city, including lumber, iron and brass, with trade in ice, but Bath is renowned for shipbuilding, which began here in 1743 when Jonathan Philbrook and his sons built 2 vessels. Since then, roughly 5,000 vessels have been launched in the area, Bath became the nations fifth largest seaport by the mid-19th century, producing clipper ships that sailed to ports around the world. The last commercial enterprise to build ships in the city was the Percy & Small Shipyard. But the most famous shipyard is the Bath Iron Works, founded in 1884 by Thomas W. Hyde who also became the manager of it in 1888. It has built hundreds of wooden and steel vessels, mostly warships for the U. S. Navy, during World War II, Bath Iron Works launched a new ship an average of every 17 days. The shipyard is a regional employer, and operates today as a division of the General Dynamics Corporation. The city is noted for its Federal, Greek Revival, and Italianate architecture, including the 1858 Custom House, Bath is sister city to Shariki in Japan, where the locally-built full rigged ship Cheseborough was wrecked in 1889. Scenes from the movies Message in a Bottle and The Man Without a Face were filmed in the city, Bath is located at 43°54′59″N 69°49′21″W

21.
Cape Cod Canal
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The Cape Cod Canal is an artificial waterway in the state of Massachusetts connecting Cape Cod Bay in the north to Buzzards Bay in the south. Part of the Atlantic Intracoastal Waterway, the approximately 7 mile long canal traverses the narrow neck of land joining Cape Cod to the states mainland. Most of its length follows tidal rivers widened to 480 feet and deepened to 32 feet at low water. Most of the canal is located in Bourne, Massachusetts, Scusset Beach State Reservation lies near the canals north entrance, the Massachusetts Maritime Academy near its south. A swift running current changes direction every six hours and can reach 5.2 miles per hour during the ebb tide. The waterway is maintained by the United States Army Corps of Engineers and has no toll fees and it is spanned by the Cape Cod Canal Railroad Bridge and two highway bridges—the Bourne and the Sagamore. Traffic lights at either end govern the approach of vessels over 65 feet, although being an artificial waterway, the canal is occasionally used by whales and dolphins including critically endangered North Atlantic right whales and can cause closure of the canal. William Bradford established the trading post of Aptuxcet in 1627 at the portage between the rivers, trade with the Native Americans of Narragansett Bay and the Dutch of New Netherland prospered and was a major factor enabling the Pilgrims to pay off their indebtedness. In 1697 the General Court of Massachusetts considered the first formal proposal to build the canal, but apparently took no action. In 1717, a canal called Jeremiahs Gutter was created in Orleans, spanning a narrower portion of the Cape some distance to the East, more energetic planning with surveys took place repeatedly in 1776,1791,1803,1818, 1824–1830, and 1860. None of these came to fruition. The first attempts at building a canal did not take place until the late 19th century. The engineers finally decided which route through the hillsides to take by connecting and widening the Manomet and Scusset Rivers, there were many problems that the engineers of the canal encountered. One was mammoth boulders left by the retreat of Ice Age glaciers, divers were hired to blow them up, but the effort slowed dredging. Another problem was cold winter storms, which forced the engineers to stop dredging altogether, nevertheless, the canal opened, on a limited basis, on July 29,1914, and it was completed in 1916. The privately owned toll canal had a width of one hundred feet, a maximum depth of 25 feet. Due to the channel and navigation difficulty, several accidents occurred which limited traffic. As a result, despite shortening the route from New York City to Boston by 62 miles

Cape Cod Canal
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The Bourne Bridge, with the Cape Cod Canal Railroad Bridge in distance
Cape Cod Canal
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Aerial photo of the East End of the Cape Cod Canal and Scusset Beach State Reservation in southeastern Massachusetts, USA
Cape Cod Canal
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Early plan (1834) that indicates a route different from what was actually constructed. (French)
Cape Cod Canal
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Bourne Bridge

22.
USS Constitution
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USS Constitution is a wooden-hulled, three-masted heavy frigate of the United States Navy, named by President George Washington after the Constitution of the United States of America. She is the worlds oldest commissioned naval vessel afloat, Constitution was launched in 1797, one of six original frigates authorized for construction by the Naval Act of 1794 and the third constructed. Joshua Humphreys designed the frigates to be the young Navys capital ships, Constitution was built in the North End of Boston, Massachusetts at Edmund Hartts shipyard. Her first duties with the newly formed U. S. Navy were to provide protection for American merchant shipping during the Quasi-War with France, the battle with Guerriere earned her the nickname of Old Ironsides and public adoration that has repeatedly saved her from scrapping. She continued to serve as flagship in the Mediterranean and African squadrons, during the American Civil War, she served as a training ship for the United States Naval Academy. She carried American artwork and industrial displays to the Paris Exposition of 1878, Constitution was retired from active service in 1881, and served as a receiving ship until designated a museum ship in 1907. In 1934, she completed a three-year, 90-port tour of the nation, Constitution sailed under her own power for her 200th birthday in 1997, and again in August 2012 to commemorate the 200th anniversary of her victory over Guerriere. The officers and crew are all active-duty U. S. Navy personnel, traditionally, command of the vessel is assigned to a Navy commander. She is usually berthed at Pier 1 of the former Charlestown Navy Yard, in May 2015, Constitution entered Dry Dock 1 to begin a three-year restoration program. In 1785, Barbary pirates began to seize American merchant vessels in the Mediterranean, in 1793 alone, eleven American ships were captured and their crews and stores held for ransom. To combat this problem, proposals were made for warships to protect American shipping, resulting in the Naval Act of 1794. The act provided funds to construct six frigates, but included a clause that, if peace terms were agreed to with Algiers, joshua Humphreys design was unusual for the time, being long on keel and narrow of beam and mounting very heavy guns. The design called for a diagonal scantling scheme intended to restrict hogging while giving the ships extremely heavy planking and this design gave the hull a greater strength than a more lightly built frigate. Humphreys design was based on his realization that the fledgling United States of the period could not match the European states in the size of their navies and this being so, the frigates were designed to overpower any other frigate yet escape from a ship of the line. Primary materials used in her construction consisted of pine and oak, including live oak. Her masts were of white pine from Maine, the keel was ultimately constructed from an alternative white oak tree, sourced from New Jersey. The name Constitution was selected by President George Washington and her keel was laid down on 1 November 1794 at Edmund Hartts shipyard in Boston, Massachusetts under the supervision of Captain Nicholson and naval constructor Colonel George Claghorn. Constitutions hull was built 21 inches thick and her length between perpendiculars was 175 ft, with a 204 ft length overall and a width of 43 ft 6 in, in total,60 acres of trees were needed for her construction

23.
Boothbay Harbor, Maine
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Boothbay Harbor is a town in the county of Lincoln, state of Maine, in the United States. The population was 2,165 at the 2010 census, during summer months, the entire Boothbay Harbor region is a popular yachting and tourist destination. The community is served by the 633 exchange in Area Code 207, the area was part of Cape Newagen, where the English established an early seasonal fishing camp. In 1666, Henry Curtis purchased the land from the sachem Mowhotiwormet, commonly known as Chief Robinhood, but the settlement was attacked and burned during King Philips War, resettled shortly afterwards, then destroyed again in 1689 during King Williams War. It was abandoned for 40 years, in 1730, Colonel David Dunbar, the superintendent and governor of the Territory of Sagadahock, laid out a new town, named Townsend after Viscount Townshend. During the Penobscot Expedition, in 1779 Townsend became a point for the American naval fleet prior to its disastrous encounter with the British at Castine. Renamed Boothbay in 1842, the continued to develop as a fishing center. In bad weather, it could hold at a time between 400 and 500 vessels, often Friendship Sloops, seeking shelter. By 1881, it had a fishery and fish oil company, on February 16,1889, the community was set off from Boothbay and incorporated as the town of Boothbay Harbor. Sample shipyard at Boothbay Harbor built minesweepers for the United States Navy during World War II, some location filming for the 1956 movie version of Rodgers and Hammersteins Carousel, notably the June Is Bustin Out All Over sequence, was done there. Each summer, Boothbay Harbor draws crowds of tourists, attractions include the state aquarium, art galleries, restaurants, boat tours to coastal islands and whale watching. According to the United States Census Bureau, the town has an area of 9.22 square miles. Boothbay Harbor is located on a peninsula in the Gulf of Maine, the town is crossed by state routes 27 and 96. It borders the towns of Southport to the southwest, and Boothbay to the north, as of the census of 2010, there were 2,165 people,1,084 households, and 550 families residing in the town. The population density was 379.8 inhabitants per square mile, there were 2,175 housing units at an average density of 381.6 per square mile. The racial makeup of the town was 97. 1% White,0. 6% African American or Black,0. 3% Native American,0. 8% Asian,0. 1% from other races, Latino of any race were 0. 7% of the population. 41. 8% of all households were made up of individuals and 22. 6% had someone living alone who was 65 years of age or older, the average household size was 1.90 and the average family size was 2.52. The median age in the town was 55.8 years

24.
Winton Motor Carriage Company
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The Winton Motor Carriage Company was a pioneer United States automobile manufacturer based in Cleveland, Ohio. Winton was one of the first American companies to sell a motor car, scottish immigrant Alexander Winton, owner of the Winton Bicycle Company, turned from bicycle production to an experimental single-cylinder automobile before starting his car company. Winton owned a large estate in Lakewood, Ohio. In the mid-1960s the home was demolished and a high rise condominium was constructed aptly named Winton Place. The company was incorporated on March 15,1897 and their first automobiles were built by hand. Each vehicle had fancy painted sides, padded seats, a leather roof, B. F. Goodrich made the tires for Winton. By this time, Winton had already produced two fully operational prototype automobiles, in May of that year, the 10 hp model achieved the astonishing speed of 33.64 mph on a test around a Cleveland horse track. Alexander Winton, in Cleveland, Ohio sold his first manufactured semi-truck in 1899, on March 24,1898, Robert Allison of Port Carbon, Pennsylvania, became the first person to buy a Winton automobile after seeing the first automobile advertisement in Scientific American. Winton sold 22 cars that year, in 1899, more than one hundred Winton vehicles were sold, making the company the largest manufacturer of gasoline-powered automobiles in the United States. This success led to the opening of the first automobile dealership by Mr. H. W. Koler in Reading, to deliver the vehicles, in 1899, Winton built the first auto hauler in America. One of these 1899 Wintons was purchased by Larz Anderson and his new wife and it is still on display at Larz Anderson Auto Museum in Brookline, Massachusetts. Publicity generated sales and in 1901 the news that both Reginald Vanderbilt and Alfred Vanderbilt had purchased Winton automobiles boosted the companys image substantially and that same year, Winton lost a race at Grosse Pointe to Henry Ford. Models Winton vowed to come back and win, producing the 1902 Winton Bullet, the Bullet was defeated in another Ford by famed driver Barney Oldfield, but two more Bullet race cars were built. In 1903, Dr Horatio Nelson Jackson made the first successful automobile drive across the United States, on a $50 bet, he purchased a slightly used 2 cylinder,20 hp Winton touring car and hired a mechanic to accompany him. Starting in San Francisco, ending in Manhattan, the trip took sixty-three days, twelve hours, jacksons Winton is now part of the collections at the National Museum of American History. The 1904 Winton was a five-passenger tonneau-equipped tourer which sold for US$2,500, models Wintons flat-mounted water-cooled straight-2, situated amidships of the car, produced 20 hp. The channel and angle steel-framed car weighed 2300 lb, models Winton continued to successfully market automobiles to upscale consumers through the 1910s, but sales began to fall in the early 1920s. This was due to the conservative nature of the company

25.
Diesel engine
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Diesel engines work by compressing only the air. This increases the air temperature inside the cylinder to such a degree that it ignites atomised diesel fuel that is injected into the combustion chamber. This contrasts with spark-ignition engines such as an engine or gas engine. In diesel engines, glow plugs may be used to aid starting in cold weather, or when the engine uses a lower compression-ratio, the original diesel engine operates on the constant pressure cycle of gradual combustion and produces no audible knock. Low-speed diesel engines can have an efficiency that exceeds 50%. Diesel engines may be designed as either two-stroke or four-stroke cycles and they were originally used as a more efficient replacement for stationary steam engines. Since the 1910s they have used in submarines and ships. Use in locomotives, trucks, heavy equipment and electricity generation plants followed later, in the 1930s, they slowly began to be used in a few automobiles. Since the 1970s, the use of engines in larger on-road and off-road vehicles in the US increased. According to the British Society of Motor Manufacturing and Traders, the EU average for diesel cars accounts for 50% of the total sold, including 70% in France and 38% in the UK. The worlds largest diesel engine is currently a Wärtsilä-Sulzer RTA96-C Common Rail marine diesel, the definition of a Diesel engine to many has become an engine that uses compression ignition. To some it may be an engine that uses heavy fuel oil, to others an engine that does not use spark ignition. However the original cycle proposed by Rudolf Diesel in 1892 was a constant temperature cycle which would require higher compression than what is needed for compression ignition. Diesels idea was to compress the air so tightly that the temperature of the air would exceed that of combustion, to make this more clear, let it be assumed that the subsequent combustion shall take place at a temperature of 700°. Then in that case the pressure must be sixty-four atmospheres, or for 800° centigrade the pressure must be ninety atmospheres. In later years Diesel realized his original cycle would not work, Diesel describes the cycle in his 1895 patent application. Notice that there is no longer a mention of compression temperatures exceeding the temperature of combustion, now all that is mentioned is the compression must be high enough for ignition. In 1806 Claude and Nicéphore Niépce developed the first known internal combustion engine, the Pyréolophore fuel system used a blast of air provided by a bellows to atomize Lycopodium

Diesel engine
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Diesel generator on an oil tanker
Diesel engine
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A Diesel engine built by MAN AG in 1906
Diesel engine
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A Hornsby-Akroyd oil engine working at the Great Dorset Steam Fair
Diesel engine
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Diesel's original 1897 engine on display at the Deutsches Museum in Munich, Germany

26.
Electric generator
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In electricity generation, a generator is a device that converts mechanical energy to electrical energy for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines, the first electromagnetic generator, the Faraday disk, was built in 1831 by British scientist Michael Faraday. Generators provide nearly all of the power for electric power grids, the reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be driven to generate electricity and frequently make acceptable manual generators. Electromagnetic generators fall into one of two categories, dynamos and alternators. The magnetic field of the dynamo or alternator can be provided by either wire windings called field coils or permanent magnets, a generator using permanent magnets is sometimes called a magneto. Armature, The power-producing component of an electrical machine, in a generator, alternator, or dynamo the armature windings generate the electric current, which provides power to an external circuit. The armature can be on either the rotor or the stator, depending on the design, before the connection between magnetism and electricity was discovered, electrostatic generators were invented. They operated on electrostatic principles, by using moving electrically charged belts, plates, the charge was generated using either of two mechanisms, electrostatic induction or the triboelectric effect. Such generators generated very high voltage and low current and their only practical applications were to power early X-ray tubes, and later in some atomic particle accelerators. The operating principle of electromagnetic generators was discovered in the years of 1831–1832 by Michael Faraday, the principle later called Faradays law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux. He also built the first electromagnetic generator, called the Faraday disk and it produced a small DC voltage. This design was inefficient, due to self-cancelling counterflows of current in regions of the disk that were not under the influence of the magnetic field. While current was induced directly underneath the magnet, the current would circulate backwards in regions that were outside the influence of the magnetic field and this counterflow limited the power output to the pickup wires, and induced waste heating of the copper disc. Later homopolar generators would solve this problem by using an array of magnets arranged around the perimeter to maintain a steady field effect in one current-flow direction. Another disadvantage was that the voltage was very low, due to the single current path through the magnetic flux. Experimenters found that using multiple turns of wire in a coil could produce higher, since the output voltage is proportional to the number of turns, generators could be easily designed to produce any desired voltage by varying the number of turns. Wire windings became a feature of all subsequent generator designs

Electric generator
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U.S. NRC image of a modern steam turbine generator (STG).
Electric generator
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Early Ganz Generator in Zwevegem, West Flanders, Belgium
Electric generator
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The Faraday disk was the first electric generator. The horseshoe-shaped magnet (A) created a magnetic field through the disk (D). When the disk was turned, this induced an electric current radially outward from the center toward the rim. The current flowed out through the sliding spring contact m, through the external circuit, and back into the center of the disk through the axle.
Electric generator
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This large belt-driven high-current dynamo produced 310 amperes at 7 volts. Dynamos are no longer used due to the size and complexity of the commutator needed for high power applications.

27.
Armature (electrical engineering)
–
The armature, in contrast, must carry current, so it is always a conductor or a conductive coil, oriented normal to both the field and to the direction of motion, torque, or force. The first is to carry current crossing the field, thus creating shaft torque in a machine or force in a linear machine. The second role is to generate an electromotive force, in the armature, an electromotive force is created by the relative motion of the armature and the field. When the machine acts in the mode, the armature EMF drives the armature current. In an induction generator, these distinctions are blurred, since the power is drawn from the stator. A growler is used to check the armature for shorts, opens, the word armature was first used in its electrical sense, i. e. keeper of a magnet, in mid 19th century. The parts of an alternator or related equipment can be expressed in either mechanical terms or electrical terms, although distinctly separate these two sets of terminology are frequently used interchangeably or in combinations that include one mechanical term and one electrical term. This may cause confusion when working with machines like brushless alternators. In most generators, the magnet is rotating, and is part of the rotor, while the armature is stationary. Both motors and generators can be either with a stationary armature and a rotating field or a rotating armature. The pole piece of a permanent magnet or electromagnet and the moving, iron part of a solenoid, the armature can be on either the rotor or the stator. Field, The magnetic field component of an alternator, generator, dynamo or motor. The field can be on either the rotor or the stator, in a DC machine, the main field is produced by field coils. In both the generating and motoring modes, the armature carries current and a field is established. The effect of armature flux on the field is called the armature reaction. The armature reaction, demagnetizes the main field, and cross magnetizes the main field, the demagnetizing effect can be overcome by adding extra ampere-turns on the main field winding. The cross magnetizing effect can be reduced by having common poles, Armature reaction is essential in Amplidyne rotating amplifiers. Armature reaction drop is the effect of a field on the distribution of the flux under main poles of a generator. Since an armature is wound with coils of wire, a field is set up in the armature whenever a current flows in the coils

28.
Two-stroke engine
–
A two-stroke, or two-cycle, engine is a type of internal combustion engine which completes a power cycle with two strokes of the piston during only one crankshaft revolution. This is in contrast to an engine, which requires four strokes of the piston to complete a power cycle. In a two-stroke engine, the end of the combustion stroke, two-stroke engines often have a high power-to-weight ratio, power being available in a narrow range of rotational speeds called the power band. Compared to four-stroke engines, two-stroke engines have a reduced number of moving parts. The first commercial two-stroke engine involving in-cylinder compression is attributed to Scottish engineer Dugald Clerk, however, unlike most later two-stroke engines, his had a separate charging cylinder. The crankcase-scavenged engine, employing the area below the piston as a pump, is generally credited to Englishman Joseph Day. The first truly practical two-stroke engine is attributed to Yorkshireman Alfred Angas Scott, gasoline versions are particularly useful in lightweight or portable applications such as chainsaws and motorcycles. In a two-stroke engine, the transfer from the engine to the cooling system is less than in a four-stroke. Two-stroke petrol engines are preferred when mechanical simplicity, light weight, the Japanese manufacturer Suzuki did the same in the 1970s. Production of two-stroke cars ended in the 1980s in the West, eastern Bloc countries continued until around 1991, with the Trabant and Wartburg in East Germany. They are also common in power tools used outdoors, such as lawnmowers, chainsaws, with direct fuel injection and a sump-based lubrication system, a two-stroke engine produces air pollution no worse than a four-stroke, and it can achieve higher thermodynamic efficiency. Therefore, the cycle has also been used in large diesel engines, most notably large industrial and marine engines, as well as some trucks. Although the principles remain the same, the details of various two-stroke engines differ depending on the type. The design types vary according to the method of introducing the charge to the cylinder, the method of scavenging the cylinder, piston port is the simplest of the designs and the most common in small two-stroke engines. All functions are controlled solely by the covering and uncovering the ports as it moves up. In the 1970s, Yamaha worked out some principles for this system. They found that, in general, widening an exhaust port increases the power by the amount as raising the port. However, there is a limit to the width of a single exhaust port

29.
Heat exchanger
–
A heat exchanger is a device used to transfer heat between a solid object and a fluid, or between two or more fluids. The fluids may be separated by a wall to prevent mixing or they may be in direct contact. They are widely used in heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing. Another example is the heat sink, which is a heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium. There are three classifications of heat exchangers according to their flow arrangement. In parallel-flow heat exchangers, the two enter the exchanger at the same end, and travel in parallel to one another to the other side. In counter-flow heat exchangers the fluids enter the exchanger from opposite ends, in a cross-flow heat exchanger, the fluids travel roughly perpendicular to one another through the exchanger. For efficiency, heat exchangers are designed to maximize the area of the wall between the two fluids, while minimizing resistance to fluid flow through the exchanger. The exchangers performance can also be affected by the addition of fins or corrugations in one or both directions, which increase surface area and may channel fluid flow or induce turbulence. The driving temperature across the heat transfer surface varies with position, in most simple systems this is the log mean temperature difference. Sometimes direct knowledge of the LMTD is not available and the NTU method is used, double pipe heat exchangers are the simplest exchangers used in industries. On one hand, these heat exchangers are cheap for both design and maintenance, making them a choice for small industries. On the other hand, their low efficiency coupled with the space occupied in large scales, has led modern industries to use more efficient heat exchangers like shell. However, since double pipe heat exchangers are simple, they are used to teach heat exchanger design basics to students as the rules for all heat exchangers are the same. Shell and tube heat exchangers consist of series of tubes, One set of these tubes contains the fluid that must be either heated or cooled. The second fluid runs over the tubes that are being heated or cooled so that it can provide the heat or absorb the heat required. A set of tubes is called the tube bundle and can be made up of types of tubes, plain, longitudinally finned. Shell and tube heat exchangers are used for high-pressure applications

30.
Electric switchboard
–
An electric switchboard is a device that directs electricity from one or more sources of supply to several smaller regions of usage. It is an assembly of one or more panels, each of which contains switches that allow electricity to be redirected, in general, switchboards may distribute power to transformers, panelboards, control equipment, and, ultimately, to individual system loads. Inside a switchboard there will be one or more busbars and these are flat strips of copper or aluminum, to which the switchgear is connected. Busbars carry large currents through the switchboard, and are supported by insulators, bare busbars are common, but many types are now manufactured with an insulating cover on the bars, leaving only connection points exposed. The operator is protected from electrocution by safety switches and fuses, the amount of power going into a switchboard must always equal to the power going out to the loads. Modern industrial switchboards are metal enclosed and of dead front construction, no energized parts are accessible when the covers, previously, open switchboards were made with switches and other devices were mounted on panels made of slate, granite, or ebony asbestos board. The metal enclosure of the switchboard is bonded to ground for protection of personnel. Large switchboards may be free-standing floor-mounted enclosures with provision for incoming connections at either the top or bottom of the enclosure, a switchboard may have incoming bus bars or bus duct for the source connection, and also for large circuits fed from the board. A switchboard may include a metering or control compartment separated from the power distribution conductors

Electric switchboard
–
A modern electric switchboard
Electric switchboard
–
Antique electrical switchboard, operational at a US plant in 2014. It features open style breakers, mounted on slabs of slate stone insulator.

31.
Propeller shaft
–
As torque carriers, drive shafts are subject to torsion and shear stress, equivalent to the difference between the input torque and the load. They must therefore be enough to bear the stress, whilst avoiding too much additional weight as that would in turn increase their inertia. The term drive shaft first appeared during the mid 19th century, in Stovers 1861 patent reissue for a planing and matching machine, the term is used to refer to the belt-driven shaft by which the machine is driven. The term is not used in his original patent, another early use of the term occurs in the 1861 patent reissue for the Watkins and Bryson horse-drawn mowing machine. Here, the term refers to the transmitting power from the machines wheels to the gear train that works the cutting mechanism. In the 1890s, the term began to be used in a closer to the modern sense. In 1899, Bukey used the term to describe the shaft transmitting power from the wheel to the machinery by a universal joint in his Horse-Power. In the same year, Clark described his Marine Velocipede using the term to refer to the shaft transmitting power through a universal joint to the propeller shaft. Crompton used the term to refer to the shaft between the transmission of his steam-powered Motor Vehicle of 1903 and the driven axle, an automobile may use a longitudinal shaft to deliver power from an engine/transmission to the other end of the vehicle before it goes to the wheels. A pair of short drive shafts is commonly used to power from a central differential, transmission. In front-engined, rear-drive vehicles, a drive shaft is also required to send power the length of the vehicle. Two forms dominate, The torque tube with a universal joint. This system became known as Système Panhard after the automobile company Panhard et Levassor patented it, most of these vehicles have a clutch and gearbox mounted directly on the engine, with a drive shaft leading to a final drive in the rear axle. When the vehicle is stationary, the drive shaft does not rotate, some vehicles, seeking improved weight balance between front and rear, use a rear-mounted transaxle. This places the clutch and transmission at the rear of the car, in this case the drive shaft rotates continuously with the engine, even when the car is stationary and out of gear. A drive shaft connecting a rear differential to a wheel may be called a half-shaft. The name derives from the fact that two such shafts are required to one rear axle. Early automobiles often used chain drive or belt drive mechanisms rather than a drive shaft, some used electrical generators and motors to transmit power to the wheels

Propeller shaft
–
Drive shaft with universal joints at each end and a spline in the centre
Propeller shaft
Propeller shaft
–
A truck double propeller shaft
Propeller shaft
–
The exposed drive shaft on BMW's first motorcycle, the R32

32.
Propeller
–
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the blade, and a fluid is accelerated behind the blade. Their disadvantages are higher mechanical complexity and higher cost, the principle employed in using a screw propeller is used in sculling. It is part of the skill of propelling a Venetian gondola but was used in a less refined way in parts of Europe. For example, propelling a canoe with a paddle using a pitch stroke or side slipping a canoe with a scull involves a similar technique. In China, sculling, called lu, was used by the 3rd century AD. In sculling, a blade is moved through an arc. The innovation introduced with the propeller was the extension of that arc through more than 360° by attaching the blade to a rotating shaft. Propellers can have a blade, but in practice there are nearly always more than one so as to balance the forces involved. The origin of the screw propeller starts with Archimedes, who used a screw to lift water for irrigation and bailing boats and it was probably an application of spiral movement in space to a hollow segmented water-wheel used for irrigation by Egyptians for centuries. Leonardo da Vinci adopted the principle to drive his theoretical helicopter, in 1784, J. P. Paucton proposed a gyrocopter-like aircraft using similar screws for both lift and propulsion. At about the time, James Watt proposed using screws to propel boats. This was not his own invention, though, Toogood and Hays had patented it a century earlier, by 1827, Czech-Austrian inventor Josef Ressel had invented a screw propeller which had multiple blades fastened around a conical base. He had tested his propeller in February 1826 on a ship that was manually driven. He was successful in using his bronze screw propeller on an adapted steamboat and his ship Civetta with 48 gross register tons, reached a speed of about six knots. This was the first ship successfully driven by an Archimedes screw-type propeller, after a new steam engine had an accident his experiments were banned by the Austro-Hungarian police as dangerous. Josef Ressel was at the time a forestry inspector for the Austrian Empire, but before this he received an Austro-Hungarian patent for his propeller. This new method of propulsion was an improvement over the paddlewheel as it was not so affected by either ship motions or changes in draft as the burned coal

Propeller
–
Propeller on a modern mid-sized merchant vessel. The propeller rotates clockwise to propel the ship forward when viewed from astern (right of picture), the person in the picture has his hand on the propeller's trailing edge
Propeller
–
Archimedes' screw.
Propeller
–
Propellers of the RMS Olympic, a sister ship to the RMS Titanic.
Propeller
–
Smith's original 1836 patent for a screw propeller of two full turns. He would later revise the patent, reducing the length to one turn.

33.
Compressors
–
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a type of gas compressor. Compressors are similar to pumps, both increase the pressure on a fluid and both can transport the fluid through a pipe, as gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible, while some can be compressed, the action of a pump is to pressurize. The main types of gas compressors are illustrated and discussed below and they can be either stationary or portable, can be single or multi-staged, and can be driven by electric motors or internal combustion engines. Small reciprocating compressors from 5 to 30 horsepower are commonly seen in applications and are typically for intermittent duty. Larger reciprocating compressors well over 1,000 hp are commonly found in large industrial, discharge pressures can range from low pressure to very high pressure. Another type of reciprocating compressor is the swash plate compressor, which uses pistons moved by a swash plate mounted on a shaft, household, home workshop, and smaller job site compressors are typically reciprocating compressors 1½ hp or less with an attached receiver tank. Rotary screw compressors use two meshed rotating positive-displacement helical screws to force the gas into a smaller space and these are usually used for continuous operation in commercial and industrial applications and may be either stationary or portable. Their application can be from 3 horsepower to over 1,200 horsepower, rotary screw compressors are commercially produced in Oil Flooded, Water Flooded and Dry type. The efficiency of rotary compressors depends on the air drier, rotary vane compressors consist of a rotor with a number of blades inserted in radial slots in the rotor. The rotor is mounted offset in a housing that is either circular or a more complex shape. As the rotor turns, blades slide in and out of the slots keeping contact with the wall of the housing. Thus, a series of increasing and decreasing volumes is created by the rotating blades, rotary Vane compressors are, with piston compressors one of the oldest of compressor technologies. With suitable port connections, the devices may be either a compressor or a vacuum pump and they can be either stationary or portable, can be single or multi-staged, and can be driven by electric motors or internal combustion engines. A rotary vane compressor is well suited to electric drive and is significantly quieter in operation than the equivalent piston compressor. Rotary vane compressors can have mechanical efficiencies of about 90%, rolling piston forces gas against a stationary vane. A scroll compressor, also known as pump and scroll vacuum pump

Compressors
–
A small stationary high pressure breathing air compressor for filling scuba cylinders
Compressors
–
A single stage centrifugal compressor
Compressors
–
A motor-driven six-cylinder reciprocating compressor that can operate with two, four or six cylinders.
Compressors
–
A three-stage diaphragm compressor

34.
Crank start
–
A starter is a device used to rotate an internal-combustion engine so as to initiate the engines operation under its own power. Starters can be electric, pneumatic, hydraulic, or in case of large engines. Internal-combustion engines are feedback systems, which, once started, rely on the inertia from each cycle to initiate the next cycle. In a four-stroke engine, the third stroke releases energy from the fuel, powering the fourth stroke, to start the first cycle at the beginning of any particular session, the first two strokes must be powered in some other way than from the engine itself. The starter motor is used for purpose and is not required once the engine starts running. The hand-crank method was used to start engines, but it was inconvenient, difficult. The behavior of an engine during starting is not always predictable, the engine can kick back, causing sudden reverse rotation. Many manual starters included a slip or release provision so that once engine rotation began. In the event of a kickback, the rotation of the engine could suddenly engage the starter, causing the crank to unexpectedly and violently jerk. For cord-wound starters, a kickback could pull the operator towards the engine or machine, or swing the starter cord and handle at high speed around the starter pulley. Even though cranks had a mechanism, when the engine started. Although users were advised to cup their fingers and thumb under the crank and pull up, it felt natural for operators to grasp the handle with the fingers on one side, the thumb on the other. Even a simple backfire could result in a thumb, it was possible to end up with a broken wrist. Moreover, increasingly larger engines with higher compression ratios made hand cranking a more physically demanding endeavour, the first electric starter was installed on an Arnold, an adaptation of the Benz Velo, built 1896 in East Peckham, England by electrical engineer H. J. Dowsing. In 1911, Charles F. Kettering, with Henry M. Leland, patent 1,150,523 for the first electric starter in America. At the voltage and current levels required, such a motor would burn out in a few minutes of continuous operation, the starters were first installed by Cadillac on production models in 1912, with the same system being adopted by Lanchester later that year. These starters also worked as generators once the engine was running, the Star and Adler cars had spring motors, which used the energy stored in a spring driving through a reduction gear. If the car failed to start the starter handle could be used to wind up the spring for a further attempt and it was still common for cars to be supplied with starter handles into the 1960s, and this continued much later for some makes

35.
Diesel fuel
–
Diesel engines have found broad use as a result of higher thermodynamic efficiency and thus fuel efficiency. This is particularly noted where diesel engines are run at part-load, as their air supply is not throttled as in a petrol engine, to distinguish these types, petroleum-derived diesel is increasingly called petrodiesel. Ultra-low-sulfur diesel is a standard for defining diesel fuel with substantially lowered sulfur contents, as of 2016, almost all of the petroleum-based diesel fuel available in UK, Europe and North America is of a ULSD type. In the UK, diesel fuel for use is commonly abbreviated DERV, standing for diesel-engined road vehicle. In Australia diesel fuel is known as distillate, and in Indonesia, it is known as Solar. Diesel fuel originated from experiments conducted by German scientist and inventor Rudolf Diesel for his engine he invented in 1892. Diesel fuel is produced from various sources, the most common being petroleum, other sources include biomass, animal fat, biogas, natural gas, and coal liquefaction. Petroleum diesel, also called petrodiesel, or fossil diesel is the most common type of diesel fuel, synthetic diesel can be produced from any carbonaceous material, including biomass, biogas, natural gas, coal and many others. The raw material is gasified into synthesis gas, which after purification is converted by the Fischer–Tropsch process to a synthetic diesel, the process is typically referred to as biomass-to-liquid, gas-to-liquid or coal-to-liquid, depending on the raw material used. Paraffinic synthetic diesel generally has a content of sulfur and very low aromatics content, reducing unregulated emissions of toxic hydrocarbons, nitrous oxides. Fatty-acid methyl ester, more known as biodiesel, is obtained from vegetable oil or animal fats which have been transesterified with methanol. It can be produced from many types of oils, the most common being rapeseed oil in Europe, methanol can also be replaced with ethanol for the transesterification process, which results in the production of ethyl esters. FAME can be used pure in engines where the manufacturer approves such use, FAME as a fuel is specified in DIN EN14214 and ASTM D6751. Pure biodiesel has an energy content about 5–10% lower than petroleum diesel, the loss in power when using pure biodiesel is 5–7%. As FAME contains low levels of sulfur, the emissions of oxides and sulfates. Use of biodiesel also results in reductions of unburned hydrocarbons, carbon monoxide, CO emissions using biodiesel are substantially reduced, on the order of 50% compared to most petrodiesel fuels. The exhaust emissions of particulate matter from biodiesel have been found to be 30% lower than overall particulate matter emissions from petrodiesel, the exhaust emissions of total hydrocarbons are up to 93% lower for biodiesel than diesel fuel. Biodiesel also may reduce risks associated with petroleum diesel

36.
Barge
–
A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. Some barges are not self-propelled and must be towed or pushed by towboats, Barge is attested from 1300, from Old French barge, from Vulgar Latin barga. The word originally could refer to any small boat, the modern meaning arose around 1480, bark small ship is attested from 1420, from Old French barque, from Vulgar Latin barca. The more precise meaning three-masted ship arose in the 17th century, both are probably derived from the Latin barica, from Greek, βάρις, translit. Egyptian boat, from Coptic, ⲃⲁⲁⲣⲉ bāri small boat, hieroglyphic Egyptian, by extension, the term embark literally means to board the kind of boat called a barque. The long pole used to maneuver or propel a barge has given rise to the saying I wouldnt touch that with a barge pole. On the British canal system, the barge is used to describe a boat wider than a narrowboat. In the United States, deckhands perform the labor and are supervised by a leadman or the mate, the captain and pilot steer the towboat, which pushes one or more barges held together with rigging, collectively called the tow. The crew live aboard the towboat as it travels along the river system or the intracoastal waterways. These towboats travel between ports and are also called line-haul boats, poles are used on barges to fend off the barge as it nears other vessels or a wharf. These are often called pike poles, barges are used today for low-value bulk items, as the cost of hauling goods by barge is very low. Barges are also used for heavy or bulky items, a typical American barge measures 195 by 35 feet. The most common European barge measures 76.5 by 11.4 metres, as an example, on June 26,2006, a 565-short-ton catalytic cracking unit reactor was shipped by barge from the Tulsa Port of Catoosa in Oklahoma to a refinery in Pascagoula, Mississippi. Extremely large objects are normally shipped in sections and assembled onsite, of the reactors 700-mile journey, only about 40 miles were traveled overland, from the final port to the refinery. Canal barges are made for the particular canal in which they will operate. Many barges, primarily Dutch barges, which were designed for carrying cargo along the canals of Europe, are no longer large enough to compete in this industry with larger newer vessels. Many of these barges have been renovated and are now used as hotel barges carrying holidaymakers along the same canals on which they once carried grain or coal. This holds true today, for areas of the world

37.
Galley (kitchen)
–
The galley is the compartment of a ship, train, or aircraft where food is cooked and prepared. It can also refer to a kitchen on a naval base. A galley is the kitchen aboard a vessel, usually laid out in an efficient typical style with longitudinal units and this makes the best use of the usually limited space aboard ships. It also caters for the rolling and heaving nature of ships, for this reason galley stoves are often gimballed, so that the liquid in pans does not spill out. They are also equipped with bars, preventing the cook from falling against the hot stove. A small kitchen on deck was called a caboose or camboose, originating from the Dutch, kombuis, in English it is a defunct term used only for a cooking area that is abovedecks. The Douglas Aircraft DC-3 was the first airplane with a galley for food service. Aircraft in operation today mainly use the airline service trolley system. The first airplane kitchen was invented by Werner Sell of Germany in 1930, in 1955 Sell also began fitting train coaches with kitchens, from 1960 on with the newly developed convection oven. Such kitchens increase storage space by working vertically, with hanging pots, dish racks, strictly, the term refers to a kitchen with the units in two facing lines, but is often used to refer to U-shaped kitchens as well. 10,000 units were installed in Frankfurt, and it was the most successful, Chief cook Chief steward Stewards assistant

38.
Hand pump
–
Hand pumps are manually operated pumps, they use human power and mechanical advantage to move fluids or air from one place to another. They are widely used in country in the world for a variety of industrial, marine, irrigation. Most hand pumps have plungers or reciprocating pistons, and are positive displacement, one sort of pump once common worldwide was a hand-powered water pump, or pitcher pump. It was commonly installed over community water wells in the days before piped water supplies, in parts of the British Isles, it was often called the parish pump. Though such community pumps are no common, people still used the expression parish pump to describe a place or forum where matters of local interest are discussed. Because water from pitcher pumps is drawn directly from the soil, if such water is not filtered and purified, consumption of it might lead to gastrointestinal or other water-borne diseases. A notorious case is the 1854 Broad Street cholera outbreak, at the time it was not known how cholera was transmitted, but physician John Snow suspected contaminated water and had the handle of the public pump he suspected removed, the outbreak then subsided. Modern hand-operated community pumps are considered the most sustainable low-cost option for safe water supply in resource-poor settings, a hand pump opens access to deeper groundwater that is often not polluted and also improves the safety of a well by protecting the water source from contaminated buckets. Pumps such as the Afridev pump are designed to be cheap to build and install, however, scarcity of spare parts for these type of pumps in some regions of Africa has diminished their utility for these areas. Suction and lift are important considerations when pumping fluids, suction is the vertical distance between the fluid to be pumped and the centre of the pump, while lift is the vertical distance between the pump and the delivery point. The depth from which a hand pump will suck is limited by pressure to an operating depth of less than 7 meters. The height to which a hand pump will lift is governed by the ability of the pump, thus the same pump and operator will be able to achieve a greater lift with a smaller diameter pipe than they could with a larger diameter pipe. Water will always try to find its lowest level, using this principle, very simple pumps with plastic or rubber bulb with flap valve at each end are used for emptying fuel or water cans into tanks. Once the bulb is full, the fluid will flow without further effort from the higher to the lower container, many hand pumps will allow the passage of fluid through them in the direction of flow and diaphragm pumps are particularly good at this. Thus where the levels are large volumes of liquid such as swimming pools can be emptied with very little effort. Direct action hand pumps have a rod that is moved up and down, directly by the user. Direct action handpumps are easy to install and maintain but are limited to the column of water a person can physically lift of up to 15 m. Examples of direct action include the canzee pump and the EMAS pump

Hand pump
–
A rural handpump in Belgium.
Hand pump
–
Cross section and details of a hand pump
Hand pump
–
A village pump can provide safe drinking water. If it is conveniently located, it can reduce the amount of time that girls and women spend carrying water.
Hand pump
–
Hand-operated, reciprocating, positive displacement, water pump in Košice - Ťahanovce, Slovakia (walking beam pump).

39.
Electro-hydraulic system
–
In automobiles, power steering helps drivers steer by augmenting steering effort of the steering wheel. Power steering can also be engineered to provide some artificial feedback of forces acting on the steered wheels, hydraulic power steering systems for cars augment steering effort via an actuator, a hydraulic cylinder that is part of a servo system. These systems have a mechanical connection between the steering wheel and the linkage that steers the wheels. This means that power-steering system failure still permits the vehicle to be steered using manual effort alone, electric power steering systems use electric motors to provide the assistance instead of hydraulic systems. As with hydraulic types, power to the actuator is controlled by the rest of the power-steering system, other power steering systems have no direct mechanical connection to the steering linkage, they require electrical power. Systems of this kind, with no connection, are sometimes called drive by wire or steer by wire. In this context, wire refers to electrical cables that carry power and data, some construction vehicles have a two-part frame with a rugged hinge in the middle, this hinge allows the front and rear axles to become non-parallel to steer the vehicle. Opposing hydraulic cylinders move the halves of the relative to each other to steer. The first power steering system on an automobile was apparently installed in 1876 by a man with the surname of Fitts, but little else is known about him. The next power steering system was put on a Columbia 5-ton truck in 1903 where an electric motor was used to assist the driver in turning the front wheels. Robert E. Twyford, a resident of Pittsburgh, Pennsylvania, francis W. Davis, an engineer of the truck division of Pierce-Arrow, began exploring how steering could be made easier, and in 1926 invented and demonstrated the first practical power steering system. Davis moved to General Motors and refined the hydraulic-assisted power steering system, Davis then signed up with Bendix, a parts manufacturer for automakers. Military needs during World War II for easier steering on heavy vehicles boosted the need for assistance on armored cars and tank-recovery vehicles for the British. Chrysler Corporation introduced the first commercially available passenger car power steering system on the 1951 Chrysler Imperial under the name Hydraguide, the Chrysler system was based on some of Daviss expired patents. General Motors introduced the 1952 Cadillac with a steering system using the work Davis had done for the company almost twenty years earlier. Charles F. Hammond from Detroit filed several patents for improvements of power steering with the Canadian Intellectual Property Office in 1958. Most new vehicles now have power steering, owing to the trends toward front wheel drive, greater vehicle mass, and wider tires, which all increase the required steering effort. Heavier vehicles, as are common in countries, would be extremely difficult to maneuver at low speeds

Electro-hydraulic system
–
A power steering fluid reservoir and pulley driven pump

40.
Winch
–
A winch is a mechanical device that is used to pull in or let out or otherwise adjust the tension of a rope or wire rope. In its simplest form it consists of a spool and attached hand crank, in larger forms, winches stand at the heart of machines as diverse as tow trucks, steam shovels and elevators. The spool can also be called the winch drum, more elaborate designs have gear assemblies and can be powered by electric, hydraulic, pneumatic or internal combustion drives. Some may include a solenoid brake and/or a mechanical brake or ratchet, the rope is usually stored on the winch. When trimming a line on a sailboat, the member turns the winch handle with one hand. Some winches have a stripper or cleat to maintain tension and these are known as self-tailing winches. Winches are frequently used as elements of mechanics to move scenery in large theatrical productions. They are often embedded in the floor and used to move large set pieces on. Winches have recently been fabricated specifically for water and snow sports and this new generation of winches is designed to pull riders swiftly across a body of water or snow, simulating a riding experience that is normally supplied by a boat, wave runner, or snow mobile. Lever winches are winches that use self-gripping jaws instead of spools to move rope or wire through the winch, powered by moving a handle back and forth, they allow one person to move objects several tons in weight. Brand names include Tirfor™ and Griphoist™ and this is a vertical spool with a ratchet mechanism similar to a conventional winch, but with no crank handle or other form of drive. The line is wrapped around the spool and can be tightened and reeled in by pulling the tail line and they also allow controlled release of the tension by the operator using the friction of the line around the ratcheted spool. They are used on small sailing boats and dinghies to control sheets and other lines, wakeskate winching is a growing hobby for many watersports enthusiasts. The winch consists of an engine, spool, rope, handle, frame, the person being towed walks away from the winch and pulls out all of the rope. When the winch is engaged, it pulls the boarder usually between 15 to 25 miles per hour, the winch may be mounted on the trailer hitch of a vehicle, set into the ground by stakes, or tied to a tree. These winches have been modified for use by skiers and snowboarders in cities, gliders are often launched using a winch mounted on a trailer or heavy vehicle. This method is used at European gliding clubs, as a cheaper alternative to aerotowing. The engine is usually a large Petrol, LPG or diesel, though hydraulic fluid engines, the winch pulls in a 1,000 to 1, 600-metre cable, made of high-tensile steel wire or a synthetic fibre, attached to the glider

Winch
–
Anchor winch of the polar research vessel Polarstern.
Winch
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Modern self-tailing winch on a sailing boat. Here, the line winched is a jib or spinnakersheet which runs from the sail (upper left, not shown) to a block (lower right,not shown) and from there to the lower part of the winch. The handle is detachable to facilitate handling of the line.
Winch
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Example of winch designed for wakeboarding. These winches consist of a small four-cycle gasoline engine, clutch, and spool all housed inside of a steel frame. A rider is towed rapidly toward the winch as the rope winds around the spool.

41.
Rudder
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A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other conveyance that moves through a fluid medium. On an aircraft the rudder is used primarily to counter adverse yaw, a rudder operates by redirecting the fluid past the hull or fuselage, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a plane or sheet of material attached with hinges to the crafts stern, tail. Often rudders are shaped so as to minimize hydrodynamic or aerodynamic drag, on simple watercraft, a tiller—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be turned by a helmsman. In larger vessels, cables, pushrods, or hydraulics may be used to link rudders to steering wheels, in typical aircraft, the rudder is operated by pedals via mechanical linkages or hydraulics. Generally, a rudder is part of the apparatus of a boat or ship that is fastened outside the hull, that is denoting all different types of oars, paddles. More specifically, the gear of ancient vessels can be classified into side-rudders and stern-mounted rudders. A third term, steering oar, can denote both types, in a Mediterranean context, side-rudders are more specifically called quarter-rudders as the later term designates more exactly the place where the rudder was mounted. Stern-mounted rudders are uniformly suspended at the back of the ship in a central position. S, a steering oar was used at this time because the rudder had not yet been invented. With a single sail, a frequent movement of the oar was required to steer a straight course. The steering oar or steering board is an oar or board to control the direction of a ship or other watercraft prior to the invention of the rudder. It is normally attached to the side in larger vessels, though in smaller ones it is rarely, if ever. Rowing oars set aside for steering appeared on large Egyptian vessels long before the time of Menes, in the Old Kingdom as much as five steering oars are found on each side of passenger boats. The tiller, at first a small pin run through the stock of the steering oar, both the tiller and the introduction of an upright steering post abaft reduced the usual number of necessary steering oars to one each side. In Iran, oars mounted on the side of ships for steering are documented from the 3rd millennium BCE in artwork, wooden models, the strength of the steering oar lay in its combination of effectiveness, adaptability and simpleness. Roman quarter steering oar mounting systems survived mostly intact through the medieval period, by the first half of the 1st century AD, steering gear mounted on the stern were also quite common in Roman river and harbour craft as proved from reliefs and archaeological finds. A tomb plaque of Hadrianic age shows a harbour tug boat in Ostia with a long stern-mounted oar for better leverage, interestingly, the boat already featured a spritsail, adding to the mobility of the harbour vessel. Further attested Roman uses of stern-mounted steering oars includes barges under tow, transport ships for wine casks, also, the well-known Zwammerdam find, a large river barge at the mouth of the Rhine, featured a large steering gear mounted on the stern

42.
Quercus alba
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Quercus alba, the white oak, is one of the preeminent hardwoods of eastern and central North America. It is an oak, native to eastern and central North America and found from Minnesota, Ontario, Quebec. Specimens have been documented to be over 450 years old, although called a white oak, it is very unusual to find an individual specimen with white bark, the usual color is a light gray. In the forest it can reach a magnificent height and in the open it develops into a massive broad-topped tree with large branches striking out at wide angles. Q. alba typically reaches heights of 80 to 100 feet at maturity, trees growing in a forest will become much taller than ones in an open area which develop to be short and massive. The tallest known white oak is 144 feet tall and it is not unusual for a white oak tree to be as wide as it is tall, but specimens growing at high altitudes may only become small shrubs. White oak may live 200 to 300 years, with even older specimens known. The Wye Oak in Wye Mills, Maryland was estimated to be over 450 years old when it fell in a thunderstorm in 2002. Another noted white oak is the Great White Oak in Basking Ridge, New Jersey, the tree measures 25 feet in circumference at the base and 16 feet in circumference four feet above the ground. The tree is 75 feet tall, and its branches spread over 125 feet from tip to tip, the oak, claimed to be the oldest in the United States, began showing signs of poor health in the mid-2010s. The tree was declared dead in 2016 and was planned to be taken down in 2017, sexual maturity begins at around 20 years, but the tree does not produce large crops of acorns until its 50th year and the amount varies from year to year. Acorns deteriorate quickly after ripening, the rate being only 10% for six-month-old seeds. As the acorns are prime food for animals and insects, all may be lost in years of small crops, the bark is a light ash-gray and peels somewhat from the top, bottom and/or sides. In spring the young leaves are of a delicate, silvery pink and covered with a soft, blanket-like down. The petioles are short, and the leaves which cluster close to the ends of the shoots are pale green and this condition continues for several days, passing through the opalescent changes of soft pink, silvery white and finally yellow green. The leaves grow to be 5 to 8.5 inches long and 2.75 to 4.5 inches wide and have a glossy green upper surface. They usually turn red or brown in autumn, but depending on climate, site, some brown, dead leaves may remain on the tree throughout winter until very early spring. The lobes can be shallow, extending less than halfway to the midrib, or deep, the acorns are usually sessile, and grow to 0.5 to 1 inch in length, falling in early October

43.
Keel
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On boats and ships, keel can refer to either of two parts, a structural element that sometimes resembles a fin and protrudes below a boat along the central line, or a hydrodynamic element. As the laying down of the keel is the step in the construction of a ship, in British. Only the ships launching is considered significant in its creation. The word can also be used as a synecdoche to refer to a complete boat, a structural keel is the bottom-most structural member around which the hull of a ship is built. The keel runs along the centerline of the ship, from the bow to the stern. The keel is often the first part of a hull to be constructed. The most common type of keel is the plate keel. A form of keel found on smaller vessels is the bar keel, which may be fitted in trawlers, tugs, and smaller ferries. Where grounding is possible, this type of keel is suitable with its massive scantlings, if a double bottom is fitted, the keel is almost inevitably of the flat plate type, bar keels often being associated with open floors, where the plate keel may also be fitted. Duct keels are provided in the bottom of some vessels and these run from the forward engine room bulkhead to the collision bulkhead and are utilized to carry the double bottom piping. The piping is then accessible when cargo is loaded, the keel surface on the bottom of the hull gives the ship greater directional control and stability. In non-sailing hulls, the helps the hull to move forward. In traditional boat building, this is provided by the structural keel, in modern construction, the bar keel or flat-plate keel performs the same function. There are many types of fixed keels, including full keels, long keels, fin keels, winged keels, bulb keels, the rudimentary purpose of the keel is to convert the sideways motion of the wind when it is abeam into forward motion. A secondary purpose of the keel is to provide ballast, keels are different from centreboards and other types of foils in that keels are made of heavy materials to provide ballast to stabilize the boat. Keels may be fixed, or non-movable, or they may retract to allow sailing in shallower waters, retracting keels may pivot or slide upwards to retract, and are usually retracted with a winch due to the weight of the ballast. Since the keel provides far more stability when lowered than when retracted, types of non-fixed keels include swing keels and canting keels. Canting keels can be found on racing yachts, such as competing in the Volvo Ocean Race

44.
Knee (construction)
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In woodworking, a knee is a natural or cut, curved piece of wood. Knees, sometimes called ships knees, are a form of bracing in boat building. A knee rafter in carpentry is a bent rafter used to gain head room in an attic, wood is a highly anisotropic material. Because wood is strongest when loaded in tension or compression along the grain, for a knee with relatively little bend, it may be possible to cut the knee out of a single straight-grained board and still achieve sufficient strength. However, with increasing bend this method becomes problematic since more and more of the knee is aligned across the grain and is considerably weaker. A knee laid out this way might easily snap in two under hand pressure alone, even if it is generously sized, in boat joinery constantly subject to shock and fatigue loading this method is unsuitable. To avoid this issue knees requiring sharper curves are made using methods which ensure that the wood grain and this can be achieved by steam bending, laminating, or selecting a natural crook with matching grain - a grown knee. Bent - Bent knees are formed by plasticizing the wood to make it flexible via boiling, steaming, or microwaving. While still hot, the wood can be bent into a suitable for the location - either on a form or by forcing and securing it directly into the final service location. Also, not all species of wood steam bend well, grown - The term grown knees refers to any knee which is made from a natural crook or bend in a tree. Grown knees can be taken from locations within a tree, with the most common being the intersection of the trunk and a large branch, crotches. The roots are a useful source as the root structure of many species of trees naturally spreads out laterally just beneath the ground in order to help anchor the tree. This provides a reliable source of approximately 90 degree crooks which may be impossible to find in other portions of the tree. Once the stump has been dug up the knees can be sawn or split from suitable natural crooks, in principle tree shaping could be used to grow a tree into the desired shape. A sharp bend in a piece of wood is called cranked. Commonly used in shipbuilding known as ship’s knee for their advantage of reducing the encroachment into the space of the structure since there is no spandrel. Also knee rafter increases the space in an attic by creating a kneewall-like space. A ship’s knee has two parts called the arm and a body, the outside surfaces come to a corner, called the heel

Knee (construction)
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Knee timbers in boat building

45.
Cypress
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Cypress is the name applied to many plants in the cypress family Cupressaceae, which is a conifer of northern temperate regions. Most cypress species are trees, while a few are shrubs, the word cypress is derived from Old French cipres, which was imported from Latin cypressus the latinisation of the Greek κυπάρισσος. Species that are known as cypresses include, The Cupressaceae family also contains 13–16 other genera that do not bear cypress in their common names. Species of cypress with very low potential for causing allergies include, Austrocedrus females and Widdringtonia females

46.
Douglas-fir
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Pseudotsuga menziesii, commonly known as Douglas fir or Douglas-fir, is an evergreen conifer species native to western North America. The common name honors David Douglas, a Scottish botanist and collector who first reported the extraordinary nature, the common name is misleading since it is not a true fir, i. e. not a member of the genus Abies. For this reason the name is written as Douglas-fir. The specific epithet, menziesii, is after Archibald Menzies, a Scottish physician, Menzies first documented the tree on Vancouver Island in 1791. Colloquially, the species is known simply as Doug-fir or as Douglas pine. One Coast Salish name for the tree, used in the Halkomelem language, is lá, one variety, coast Douglas fir, grows in the coastal regions, from west-central British Columbia southward to central California. In Oregon and Washington, its range is continuous from the edge of the Cascades west to the Pacific Coast Ranges. In California, it is found in the Klamath and California Coast Ranges as far south as the Santa Lucia Range, in the Sierra Nevada, it ranges as far south as the Yosemite region. It occurs from sea level along the coast to 1,800 m above sea level in the mountains of California. Further inland, coast Douglas fir is replaced by another variety, mexican Douglas fir, which ranges as far south as Oaxaca, is often considered a variety of P. menziesii. Coast Douglas fir is currently the second-tallest conifer in the world. Extant coast Douglas fir trees 60–75 m or more in height and 1. 5–2 m in diameter are common in old growth stands, Douglas firs commonly live more than 500 years and occasionally more than 1,000 years. The bark on trees is thin, smooth, and gray. On mature trees, it is thick and corky, the shoots are brown to olive-green, turning gray-brown with age, smooth, though not as smooth as fir shoots, and finely pubescent with short, dark hairs. The buds are a distinctive, narrow, conic shape, 4–8 mm long. Unlike the Rocky Mountain Douglas fir, coast Douglas fir foliage has a noticeable sweet fruity-resinous scent, the mature female seed cones are pendulous, 5–8 cm long, 2–3 cm wide when closed, opening to a 4 cm width. They are produced in spring, green at first, maturing orange-brown in the autumn 6–7 months later, the seeds are 5–6 mm long and 3–4 mm wide, with a 12–15-mm wing. The male cones are 2–3 cm long, dispersing yellow pollen in spring, in forest conditions, old individuals typically have a narrow, cylindric crown beginning 20–40 m above a branch-free trunk

47.
Pinus classification
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Pinus, the Pines, is a genus of approximately 111 extant tree and shrub species. The genus is split into two subgenera, subgenus Pinus, and subgenus Strobus. Each of the subgenera have several sections based on chloroplast DNA sequencing. Older classifications split the genus into three subgenera – subgenus Pinus, subgenus Strobus, and subgenus Ducampopinus – based on cone, seed, DNA phylogeny has shown that species formerly in subgenus Ducampopinus are members of subgenus Strobus, so Ducampopinus is no longer used. The species of subgenus Ducampopinus were regarded as intermediate between the two subgenera. In the modern classification, they are placed into subgenus Strobus, in 1888 the Californian botanist John Gill Lemmon placed them in subgenus Pinus. In general, this classification emphasized cone, cone scale, seed, and leaf fascicle and sheath morphology, Pines with one fibrovascular bundle per leaf, were known as haploxylon pines, while pines with two fibrovascular bundles per leaf, were called diploxylon pines. Diploxylon pines tend to have harder timber and an amount of resin than the haploxylon pines. Subgenus Pinus includes the yellow and hard pines, section Pinus is mostly in Europe, Asia, except for P. resinosa in northeast North America and P. tropicalis in Cuba. Subsection Pinus P. densata - Sikang pine P. densiflora - Japanese red pine P. fragilissima P. henryi, P. hwangshanensis - Huangshan pine P. kesiya - Khasi pine P. latteri. †P. peregrinus - Pinus peregrinus - Middle Eocene, Golden Valley Formation, North Dakota, NCBI Taxonomy server files Ducampopinus species above as Strobus